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The primary role of ecosystems along with its all constituents is, at least to sustain life on earth. They facilitate all the living things with vital needs, known as ecological goods and services within their particular systems; those include provision of food and water; regulation of climate and disease; supporting nutrient cycles.
Diversity exists in ecosystems whether terrestrial, aquatic, tropical, and temperate and they also provide vast variety among living organisms. Both theoretical and empirical studies suggest that within these living communities, competitive interaction exists, between various plants life, animal life, amongst similar and dissimilar species and amongst the plants and animals, which is the key determinant of species abundance and diversity (ZHOU et al. 2002).
Another important feature about ecosystems is its ability to clean, recycle and absorb/removal of pollutants and contaminants that is present in air, soil or waters. It is also important that ecosystems should not be disturbed with through anthropogenic activities because of its delicate nature. If such activities are essential and have to be proceeded, then balance should be established between the ecosystem to sustain it and anthropogenic activities. Undisturbed ecosystems also serve as a genetic pool of biodiversity, not only for the balance of nature, but also to pharmaceuticals searching the far corners of the world for the miracle drug to cure the deadliest diseases. The demands of people is increasing as human population in many regions is rising day by day, its associated demand for development, industrialization and other related activities, most of the ecosystems are increasingly coming under threat and overburdened by pollution, degradation and destruction.
Environmental degradation is a global phenomenon, but is significantly more deleterious in the developing countries, which house the largest populations of human inhabitants, within considerably smaller area. Such a large population comes with the demand for development, especially in the agriculture sector, the need for economic growth and industrialization, often at the expense of the environment.
Industrial development results in the generation of industrial effluents, and if disposed untreated then they results in water, sediment and soil pollution (FAKAYODE AND ONIANWA, 2002Í¾ FAKAYODE, 2005). Industrial effluents and emissions had lethal and harmful substances, most of them are disastrous to human beings (RAJARAM et al. 2008; OGUNFOWOKAN et al. 2005; JIMENA et al. 2008).
In current decades, industrial effluent release from different sources consisting heavy metals that cause an increase in resistant bacterial population. This dilemma is significantly more familiar in the industrial areas, that has been discharging waste water continuously into the water bodies causing the heavy metals to be captivated in the soil particles (clay especially) and transport it to distant areas from the discharging point.
The beginning of rapid industrialization, development and urbanization, all driven by the exceptional population growth rate, has directly disturbed the environment. Today, the resultant degradation and contamination of the ecosystems has become a major threat for all life on earth, in general, and humanity, particular. Of course we have no mean right to blame development only for the environmental disaster that we face today, in fact, it is mismanagement and lack of planning, particularly in Pakistan, which has led humanity to the point where the environment that once sustained life is now the harbinger of decay, disease and death (EPA, 1990).
Pakistan, also, is not expelled from such devastating and degrading environmental conditions resulted from different pollutants, as its population is growing day by day, almost 186 million in 2012 (GOVERNMENT OF PAKISTAN 2012). Therefore the agricultural and industrial sectors's economic activity has been enhanced phenomenally. At the same time, less priority has been given to the treatment of and dumping of waste materials, that resulted in significant increased level of pollutants in water, air and soil during the last 20 years. (IUCN, 1994; KHAN et al. 1997; KHAWAJA, 2000).
Most of the waste generated by industries, is in the form of solids, effluents or gases, that is directly discharged into air, water bodies and adjacent lands without any prior treatment or detoxification (HANNIF, 1991). Contamination with xenobiotics has been reported to influence the functioning of the overall ecosystem not only by affecting the quality of the natural resources including land and water but also by entering the food chain and having the adverse effect on humans, plants, animals and microorganisms (MROZIK et al. 2003; SWEETMAN et al. 2005; VALLOTTON et al. 2009; WIDENFALK et al. 2008 AND EL-AZHARI et al. 2010).
In Pakistan, the recent trending shift from agriculture to different industries has further enhanced the environmental degradation. A number of textile mills, cement, edible oil, paint, fertilizer, tanneries and other chemical factories have been established throughout the Pakistan, which termed as industrial areas. The industrial areas are mostly situated near urban centers, along river and waterways. According to the Environment Protection Agency (EPA), in Pakistan, the industrial effluents being dumped into waterways and on the land, by the electroplating tanner industries alone contain toxic metals such as Chromium (Cr), Nickle (Ni), Arsenic (As), Mercury (Hg), Copper (Cu) and Lead (Pb). These metals have contaminated the soil and the biota residing in such soils in Pakistan (EPA, 1990). In Faisalabad, different studies have reported that the city effluents, which comprise of both domestic as well as industrial waste contain Pb, Cu, Cd and other hazardous heavy metals (KHAN et al., 1992). As a result, immense curiosity has arisen in metal-microbe relation nowadays, as scientists and industrialists are trying to find out that how they can eliminate, recover or alleviate heavy metals in effluents and soils (SANI et al. 2001). Such toxins tend to persist in the environment, accumulating in the biota, thereby entering the food chain causing deleterious harm to higher animals and humans' alike (ZHANG et al.1998).
Conventionally, the removal of heavy metal ions from industrial effluents and polluted soil has been achieved through different chemical and physical methods. Such procedures include precipitation, ion exchange, electrolysis technologies, chemical extraction, leaching, hydrolysis, polymer micro-encapsulation and the most commonly practiced excavation and land filling (KHAN et al. 1997).
However, most of these techniques are very expensive to implement at large scale and are dangerous in themselves, requiring constant monitoring and control, sometimes not resulting in the complete removal of the contaminant (YERUSHALMI et al. 2003).
Analyzing the cost of bioremediation and comparing them to that of physical/chemical treatment for cleaning the environment, there seems to be no doubt as to which method should be employed, especially in areas where the contamination levels are low and/or the duration of contaminant less than 20 years (ATLAS AND UNTERMAN, 1999).
At least 20 metals are classified as toxic with half of them emitted into the environment that poses great risks to human health (AKPOR AND MUCHIE, 2010). The common heavy metals like Cd, Pb, Co, Zn and Cr etc. are toxic at both low concentration as well as very high concentration found in waste water. Each heavy metal has unique biofunctions or biotoxicities.
The heavy metals biodegradation by using microbes has received a great deal of interest by researchers in current years, not only as a scientific innovation but also for its latent potential in various industries. Microbes play a massive task in the hazardous heavy metal's biogeochemical movement in ecosystem and also in eliminating or remediating heavy metal-contaminated environments (soil, water etc). Microscopic organisms have adapted to a variety of changes for adjustment according to the presence of toxic heavy metals. There are a numerous evidences for the advancement of heavy metal resistance in innate microbial populations, residing at contaminated sites. The microbes act in response to these metals by different procedures; comprising of precipitation, biosorption to the cell walls and snarement in extracellular capsules, transport across the cell membrane, complexation and oxidation-reduction reactions (RAI et al. 1981; AVERY AND TOBIN, 1993; BRADY et al. 1994 AND VEGLIO et al. 1997).
Bacterial resistance capabilities are extensive and abundant, with different frequencies of bacterial resistance ranging from a little chances of resistance in unpolluted environments to nearly all isolates in heavily contaminated sites (SILVER AND PHUNG, 2005). Microbial communities inhabiting in heavy metal contaminated sites, adapted themselves to hazardous levels of heavy metals and become resistant to metal (PRASENJIT AND SUMATHI, 2005).
Heavy metals are not eco-friendly and recyclable. They have a tendency to be magnified in organism's body causing various hazardous diseases and abnormalities (OZER AND PIRINCCI, 2006). Human infections caused by such bacteria could be difficult to treat with drugs. Various studies had shown the adverse effects of toxic heavy metals on plants, animals and human health (CHISTI, 2004; CHIPASA, 2003).
Lead is naturally present micro element usually occur in trace amounts in all the biological resources like water, soil, animals and plants. Lead is a metallic element that occurs naturally and mainly existed in the crust of the earth in the order of 15 g/ton. Generally, the pure form of lead does not existed, but various mineral forms of lead were commonly founded i.e. lead sulfate, lead carbonate and lead sulfide etc. According to the NEUMANN et al. (1990) organisms have no physiological function from lead. CIBULKA stated that the lead contamination's main sources are transport, rain, hail, snow, smelting works, treatment sludge of wastewater's application to soil and others. Human activities originated the lead into the atmosphere by 98 Vo, approximately. The extended sources responsible for lead pollution are cell batteries, lead wastes, lead solders and forms and paints (NEUMANN et al. 1990).
Among all the pollutants, lead (Pb) is most difficult pollutants to manage and control (SALT et al. 1998) and one of the most abundant toxic metals that cause a serious threat to human beings, animals and microorganisms. Different adverse effects on human health have been reported due to the lead exposure (SMITH; 1984, TONG; 1998; KAZANTZIS; 1989). In human, it is absorbed directly into the blood stream and is stored in soft tissues, bones and teeth (95% in bones and teeth) (WIN et al. 2003). It can also affect the kidney, nervous system and brain and most importantly, it can accumulate over a lifetime causing diseases such as anemia, encephalopathy, hepatitis and nephritic syndrome. The WHO (2004) allowable standard for lead is 0.15 mg/L. In certain conditions it exceeds and constant exposure may lead to delay in psychological or physical growth in infants and kids while adults may suffer from nephropathy and hypertension. Lead contaminates water by the corrosion of household plumbing system and erosion of natural deposits (US EPA, 2005).
Plants absorbed lead through roots and the majority of the lead concentration is also accumulated in them. In contrast to the roots uptake, the lead content reduced in the sequence as follows: above ground part are greater than roots while products are less than roots (CHRENEKOVAL, 1984). Animal's lead intoxication mainly occurs after grazing on lead polluted pasture (ZELEZNIK, 1994). In the organisms, lead enters through air and food and further bioaccumulation occur in them. In children's, mostly central nervous system is affected by lead concentration. At prenatal stage, lead toxic effects cause birth weight reduction, mental development retardation and gravidity shortening (ratio of premature babies increase).
Microorganisms along with microbial products might be extremely competent bio accumulators for particulate and soluble metals forms particularly diluted external solutions. Since the bacterial resistance based on their form and environment as well as on physical factors like substances concentration and their type, although, significantly resistant microorganisms may reveal their environmental condition.
Technologies related to microbe may offer a substitute or other than the usual method for metal removal or recovery. Isolation of lead tolerant bacteria (TRAJANOVSKA et al. 1997) and lead phosphate precipitation in the bacterial cells has been documented in 1990's. (LEVINSON et al. 1996; LEVINSIN AND MAHLER, 1998).
Heavy metal resistant bacteria have significant role in bioremediation of heavy metals in wastewater. Therefore keeping in view, the hazardous environmental and health impact of lead, present study was conducted mainly focusing to explore the naturally occurring bacteria acting as a bioremediating agent. Specific objectives of the study were
Analysis of physicochemical analysis of effluent samples to assess the impact of pollution
Isolation of lead resistant bacteria from waste water.
Purification of isolated lead resistant bacterial strains.
Screening and enumeration of potential lead remediating bacterial strains.
Biochemical characterization of potential lead resistant bacterial strains.
Review of literature
In 1985, KIM studied the heavy metals effect on natural population of bacteria lied under underground water and surface microlayer. He used 14C-glucose uptake rate and bacterial colony forming as study parameters. He found that two natural bacterial strains exhibited various reactions against heavy metals. Presence of populations of autochthonous bacterioneuston in the marine environment was supported by the results.
NOLAN AND SHAIKH (1992) conducted a study to evaluate the toxic effect of color black of lead on body system and summarized the lead toxic effect on the kidney and discovers the kidney problem mechanisms as well as other related disorders induced from lead toxicity.
ADHIKARI et al. (1993) collected sewage effluents at different discharge points of Calcutta city (India) and found neutral to slightly alkaline pH with high soluble salts, while concentration of Cu, Cr, Mn, Pb, and Cd ranged from 0.5 to 3.35, traces to 29.25, 2.30 to 37.80, 5.00 to 18.00 and traces to 3.80 mg L-1, respectively.
LEUNG et al. (1993) evaluated the lead level in two thousand, nine hundred and twenty one samples of blood collected from children under 16 and adults(female and male) retrospectively. They took a suggested value of 0.48 Î¼mol/L for females and children and 0.72 Î¼mol/L for males. They noted from readings that males were above 70% while females and children were less than 80% lied within the reference values and suggested that there would be less risk of lead (Pb) toxicity. They assessed zinc protoporphyrin as a diagnostic apparatus to check the presence of lead in blood from results via likelihood ratios and curves of receiver operating characteristic. Their study confirmed that zinc protoporphyrin (ZPP) had not recognized the increased level of lead in blood at the significant limits (0.48-1.21 Î¼mol/L) in adult females and children with subclinical lead toxicity. The results showed that zinc protoporphyrin (ZPP) was more efficient in evaluating the higher level of lead in males professional worker diagnostically.
ROANE AND KELLOGG (1996) analyzed heavy metal impacted soil and microbial communities causing adverse effect on biomass. A number of autochthonous cadmium(Cd) and lead (Pb) resistant strains and their metabolism were also evaluated. The communities of microorganism comprised of 2 populations that was found to be either sensitive or resistant to lead (Pb). A strain resistant to lead was isolated from a controlled soil (with no known contact to lead previously), revealing extensive microbial resistance against lead. Pseudomonas sp, Corynebacterium sp, Enterobacte sp and Bacillus sp were lead resistant isolates. Through typical purification, plasmids ranged within 5 to 260â€‚kb, had not identified from lead-resistant isolates. Optimistic correlations between antibiotic confrontation and isolation habitat of lead resistant bacteria, form of soil, lead soluble concentration, variety of microbes, total bacterial counts and arsenic (As) concentration was reported.
ALI (1997) reported that the sewage water without any treatment is mainly disposed into nearby rivers or surface drains. Concentration of Cr, Cu, Pb, Mn, Hg, Ni and Cd at the main outfall sewage of the Lahore city was 1.29, 1.20, 1.10, 2.00, 0.003, 0.006 and 0.007 mg L-1, respectively which was because of dilution due to water transported from the River Jehlum through the Rasoo Qadirabad Balloki link canals.
CIBA et al. (1999) carried out the separation of organic fraction of municipal wastes on the laboratory scale. The concentration of cadmium, cobalt, copper, manganese, nickel, lead and zinc present in the obtained compost were determined, as well as the speciation by making use of Rudd's method of sequential extraction. The way of removing these metals from the compost by means of leaching with solutions of H2SO4 and HNO3 was concerned in the investigation, as well as separating the metals from the solution, electrochemically, after the compost had been leached with H2SO4. It was found that the application of the electrochemical method with varying pH values of the leaching solution within the range of 6.8-2.8 allowed for the separation of 83.5 % Cd, 55.0 % Co. 65.4 % Cu, 59.4 % Mn, 70.3 % Ni, 90.5 % Pb and 56.2 % Zn.
LI (2001) evaluated the resistance of lead (Pb), zinc (Zn), cesium (Ce), mercury (Hg) and arsenate (Ar) in 8 Pseudomonas sp. that were resistant to copper (Cu) resistant strains that was previously isolated from Torch Lake sediments. Variable susceptibility to different antibiotics was showed by those strains. Those populations resistant to heavy metals had ability to accumulate different concentrations of various metals and solubilization of copper (Cu). Microbial isolates showed aptitude to bioaccumulate the zinc (Zn) up to 15.9 mgg-1 dry cell and lead (Pb) upto 80.7 mgg-1 dry cell. All the isolates produced plant growth promoting iron chelating siderphore, phosphate solubilization, indole acetic acid and metals. By using Pseudomonas sp. TLC 6.6-5.5 that produced higher metal and phosphate solubilization and indole acetic acid (IAA), they investigated the effect of Pseudomonas sp inoculation on the growth of plants and copper (Cu) uptake by sunflower and maize, that caused a significant rise in copper(Cu) accumulation in sunflower and maize, also caused an increase maize biomass. They characterized bacterial isolates that were resistant to different heavy metal and suggested its potential role in bioremediation of metal contaminated water, soils and plants.
YAZDI (2001) identified the bacterial population that was involved in the laboratory activated sludge unit. Gram negative bacilli with a yellow pigment was the major group of the population as shown by the obtained results.
In 2002, RAHMAN et al. studied diseases in children caused by lead, affecting their mental and physical abilities in Karachi. They conducted a survey in seven schools of Karachi. From class 1-3 (mostly between 6-10 years old), they gathered the samples of blood and shedded maxillary teeth, then further analyzed by atomic absorption spectrophotometry(AAS) for lead (Pb). Over 80% had lead levels above safe confines out of 138 children, given by the United States Centers for Disease Control and Prevention (USDCP).
GUMMERSHEIMER AND GIBLIN (2003) used a bioremediation strategy to recognize candidate bacterial strains that were able to modify the contaminant. The main objectives of their project were i) to observe bacteria that was found in lead contaminated soil ii) to resolute the level of lead resistance of native bacteria iii. to determine whether those lead resistance mechanisms were carried on a plasmid. They isolated four different bacteria with high levels of resistance to lead and every bacterium showed resistance to 2 mM lead on minimal medium. They identified that two were as Gram positive Corynebacterium and two belonged to the Gram negative genus Pseudomonas. They found that three out of four isolates conceded no obvious plasmid, signifying that the metal resistance was chromosomally encoded.
HUSSAIN et al. (2003) presented the results of a study which was conducted in Faisalabad to check the environmental pollution impact on human behavior and strengthen of awareness level through mass media along with the people of the study area.
Ilhan et al. (2004) investigated selective biosorption of lead, chromium and copper ions by microbes from industrial effluents. They isolated microbes from soil and a bacterium that was identified as Staphylococcus sapprophyticus was used. They investigated the effects of temperature, pH and initial concentration of heavy metal ions on the biosorption capacity. The optimum pH values for lead, chromium and copper biosorption was obtained as 4.5, 2.0 and 3.5 respectively. They observed highest adsorption for Pb, Cr and Cu at initial concentration of 100mg Pb/l, 193.66 mg Cr/l and 105 mg Cu/l.
BEGONIA et al. (2005) used a technique to remediate the pollution by using plants instead of mechanical based technology which was undoubtly an expensive technique. They carried out experiments to evaluate the appropriateness of phytoremediation of plants species. They found that Festuca arundinacea Schreb. (tall fescue) could be more resistant to pollutants and could store a significant amount of lead (Pb) in its stems from their previous study, when it was grown in lead contaminated sand. They additionally assessed tall fescue fitness among species that was more crop rotation tolerant phytoextraction. They determine if the addition of EDTA (ethylene diamine tetra acetic acid) separately or in permutation within acetic acid might be improved additionally lead uptake from the shoot. They grew seeds in 3.8 L synthetic pots had sand, peat and top soil (1:2:4, v: v: v) spiked with different levels (0 mg Pb/kg,1000 mg Pb/kg, 2000 mg Pb/kg dry soil) of Pb (lead). After 6 planting weeks, EDTA and acetic acid aqueous solutions were used to the zone of root, and all plants were harvested after a week. It was showed by the results that tall fescue had comparatively more ability to optimum Pb levels. Lead contents in root augmented with the increase in lead applied by soil. In addition, lead content increases in root were attributed to the amendment of chelate. Metal partitioning measurement to the shoots along with the index of translocation, was significantly high with extra chelate particularly when acetic acid and EDTA were used. Higher lead concentration in shoot was lead by the increase in induced chelate in the indices of translocation likewise.
In 2005 AGHA et al. assessed the effects of lead (Pb) toxicity in Islamabad. Concentration of lead in blood samples, taken from forty seven male traffic police officers (between 21- 45 years) was measured. The male traffic wardens were controlling the traffic for three to eighteen months, eight hrs in a day and six days in a week. Young males constables (from 13to19 years) were included as controls, who were living in a better, clean and low traffic residing in comparatively clean and low traffic areas. They measured the concentration of lead (Pb) by using atomic absorption spectrophotometer (AAS). The reported average concentration of lead in blood of traffic police constables was 27.27 Î¼g/dl which was more in concentration as compared to average level of lead in blood of controls, 3.22 Î¼g/dl.
SAIF et al. (2005) tested industrial effluent mixed with domestic waste water that was used as irrigation water to irrigate the vegetables growing in the area of Korangi to detect the concentration of different toxic heavy metals. They collected total 24 samples of effluents from different drains and four tube wells, also soil and plants samples from same area to analyze the heavy metal concentration in the year of 2000. They observed that zinc (Zn) was 0.005-5.5 mg/L, copper (Cu) 0.005-1.19 mg/L, iron (Fe) 0.04-5.58 mg/L, magnese (Mn) 0.01-1.79 mg/L, cadmium (Cd) 0.004-2.4 mg/L, chromium (Cr) 0.004- 5.62 mg/L, nickle (Ni) 0.02-5.35 mg/L and lead (Pb) 0.05 to 2.25 mg/L in different effluent samples. They noted that zinc, chromium, copper and iron were present in 4% of the samples which was above the threshold limits while 7% samples contained manganese, 21% samples had lead, 14% of samples had nickel and cadmium was present in 36%of samples. The concentration of heavy metals was above the permissible limits in these samples. Zinc, lead, manganese, cadmium, iron and nickel values were found to be higher in analysis of soil from the depth of 7.5 inch in some areas. Higher level of heavy metals was observed in spinach as compared to the permissible limit. Vegetation that was irrigated with water of tube well was safe from heavy metals contents and was within the safe limits.
SMIRJDKOVA et al. (2005) studied the risks related to health including toxicity or absorption of toxic materials in food, consumed amount of toxic food and time duration of exposure caused by environmental contaminants. They concerned about complex nature of chemicals and suggested that the toxicity of pollutants should be extrapolated from animal experimentation. Whether the substances caused the same adverse effect in humans or not hadn't confirmed with certainty. They observed that contaminated food products were the major cause of cadmium (Cd) exposure to humans except for those industrial areas releasing cadmium. Cadmium taken up by roots of plants and passed to edible parts of plants, indirectly accumulated in animals and their milk. That was the main cause of cadmium (Cd) exposure to people, when they consumed Cd polluted plants or animals. Bioaccumulation of lead in all food of animal origin with the exception of milk was in higher contents than the plant source. The mean lead ingestion was less than 70 VoI weekly. The PTWI values were measured on the base of food consumption and the significant values of lead in food.
NASRULLAH et al. (2006) conducted a study to analyze the contamination in underground water of three tube wells from different sites and industrial effluents of Gadoon Amazai (industrial area), Swabi, North western frontier province. They identified the sites and collected effluent samples from 8 different industries including marble, ghee, oil, chemical, textile, soap, and steel industries. They analyzed the samples for various physicochemical parameters such as pH, total suspended solids (TSS), total dissolved solids (TDS), electrical conductivity (EC) and heavy metals contents. The potential hydrogenii (pH) of effluent samples ranged from 6.47 to 8.48 with electrical conductivity (EC) lied between 0.258 to 0.865dSm-1, temperature was found from 26.9-30.2°C, TDS from 143-1050 ppm, TSS 140.5-1670.8 ppm and biological oxygen demand (BOD) ranged between 72.9 to 463.7 ppm. pH ranged between 6.82-7.9 with EC 0.351-0.511dS/m, TSS of ground water was between 1.78-2.0 ppm, BOD was in range from 0.294-0.802 ppm, temperature lied between 26.0-26.7oC and TDS with 139-513 ppm showed by the samples of ground water. The concentration of nickel (Ni), lead (Pb), cadmium (Cd), chromium (Cr) and copper (Cu) were in the range of 0.009 to 0.794, 0.20 to 2.84, 0.003 to 0.043, 0.004 to 0.28 and 0.381 to 1.136 ppm, respectively found in the industrial effluents samples. While manganese (Mn), zinc (Zn) and ferrous (Fe) was from 0.014-0.163, 0.003-0.097 and 0.008-4.5611ppm, respectively. The results of ground water samples indicated the nickle (Ni) and lead (Pb) concentration was between 0.030 -0.066 ppm and 0.007 to 0.025 ppm,respectively, Cr was found to be in the range of 0.017- 0.111 ppm, Cd was found between 0.21 to 1.20 ppm, Fe was from 0.004 to 0.037 ppm, Cu and Zn were from 0.780 - 0.893 ppm and 0.007 - 0.066 ppm, respectively and Mn was from 0.059 to 0.164 ppm.
SIAL et al. (2006) collected and then analyzed the various industries sewage, tap water and effluents for pH, EC (electrical conductivity), TSS (total soluble salts), BOD (biological oxygen demand), COD (chemical oxygen demand), total N, anions, cations as well as heavy metals. The highly alkaline effluents were from textile and ghee industries. The load of Electrical conductivity (EC) and total soluble salts (TSS) loads of textile and ghee industries were beyond the NEQS of Pakistan. Carbonates, bicarbonates and RSCs (residual Na2Co3) were present in all the effluents while the load of toxic metals was beyond the limit for example 2.0 mg/L.
YAN et al. (2007) examined the bacterial population in activated sludge system. They discussed the set procedure, medium used, analytical methods and biochemical characterization techniques required for isolation, and identification of bacteria that were responsible for the key process of wastewater treatment systems (nutrient removal, aerobic, anaerobic, etc.). They observed the effect of seasonal (summer and winter) temperature variations and salinity change on the bacterial species for wastewater treatment. Additionally, microbial activities effected from SMP (soluble microbial products) that were among the significant factors and thus affected the effluents quality from systems to treat wastewater biologically. In their paper, they also covered the identification, characterization, significance, and implications of SMP in the context of activated sludge processes.
RAJA et al. (2006) isolated and characterized the microorganisms that were resistant to metal from the wastewater sample of treated oil mill industry. The screening of metal resistant bacteria showed MIC values towards metals (Pb, Ni, Cd and Cr) ranged to the level of 100-800 ppm. Wastewater samples isolate BC15 was recognized as Pseudomonas sp. Isolates Biochemical, morphological and 16S rDNA sequence detailed analysis revealed that was directly related to Pseudomonas aeruginosa (94 %). Pseudomonas BC15 had the ability to absorb 65% Pb, 50% Cd, 30% Cr and 93 % Ni in 48 hours from the media containing 100 mg/l of all heavy metal. Particular strain's multiple tolerance to metal was also related with resistance against antibiotics like ampicillin, chloramphenicol, erythromycin, kanamycin, streptomycin and tetracycline.
SINGH AND CHANDEL (2006) characterized different industrial effluents heavy metals, some of them; Pb, As, Fe, Cd, Cr, Cu, Mn, Ni and Zn. It was revealed by the results that Pb, Cd, Cr and As were not present in any wastewater samples, but some heavy metals ranging from: Ni (0.0. - 0.07 mg/L), Fe (0.1. - 0.4 mg/L), Mn (0.0. - 0.4 mg/L), Cu (0.0. - 1.0 mg/L) and Zn (0.68. - 60.84 mg/L). However, Nickel was lower than the regulated safety limits.
AHAMED AND SIDDIQUI (2007) carried out a study which indicated that there was a efficiency and safety deficiency when used usual chelating agents. To conclude the nutrient supplementations favorable effect following lead exposure, several studies were underway. Data suggested that nutrients can play a significant role in reducing some lead toxic effects. They addressed and explain the exogenous nutrients use significance in the treatment of lead toxicity in environment (i) various lead exposure sources and/or current level of lead in blood and (ii) protecting effects of nutrients supplementation in toxicity of lead.
KERMANSHAHI et al. (2007) evaluated bacterial resistant to metals in the Isfahan Province soil. The soils were classified according to the sampling locations such as non agricultural soils, agricultural soils and sediments of the Zayanderood Riverbank. It was recognized the resistant bacteria to Pb (2mM), Cd (0.5 mM), Cu (5 mM) and As (5 mM), while in later stages, MIC was determined for the bacterial resistant growth to metals. Metal uptake rates and dry cellular for the bacterial resistant to metals was also determined by them.
REHMAN et al. (2007) assessed the capability of 2 Hg2+ resistant bacterial strains, Brevibacterium casei and Pseudomonas aeruginosa, to uptake metal by the media. The MIC of Hg2+ ranged between 400-500 Î¼g/mL for the bacterial isolates, Pseudomonas aeruginosa could tolerate Pb2+ (600 Î¼g/mL), Cd2+ (50 Î¼g/mL), Cu2+ (200 Î¼g/mL), Ni2+ (550 Î¼g/mL), Zn2+ (50 Î¼g/mL), and Cr6+ (50 Î¼g/mL). Brevibacterium casei, on the other hand, showed resistance against Pb2+, Cd2+, Cr6+, Cu2+, Ni2+, Zn2+ and on the concentration of 650, 50, 150, 200, 550, 50 Î¼g/mL, respectively. The isolates showed typical growth curves but lag and log phases extensive in the presence of mercury. Optimum growth at 37 °C was showed by both isolates and pH varying from 7-7.5. They determined the processing ability of metal isolates in the media containing 100 Î¼g/mL of Hg2+. Pseudomonas aeruginosa could reduce 93% of mercury from the medium after 40 hours and was also able to remove Hg2+ 35%, 55% 70% and 85% from the medium after 8, 16, 24 and 32 hours, respectively. Brevibacterium casei could also efficiently remove 80% mercury from the medium after 40 hours and was also able to remove Hg2+ 20%, 40%, 50%, and 65% from the medium after 8, 16, 24 and 32 hours, respectively. Both bacterial strains had shown highly capable to uptake metal ions from the culture medium. Pseudomonas aeruginosa was observed to uptake 80% and Brevibacterium casei 70% of Hg2+ from the medium after 24 hours of incubation at 37oC. The metal uptake ability suggested the possibility of using these bacterial strains for removal of mercury from Hg2+ contaminated wastewater.
Several heavy metal resistant bacterial strains were isolated from sediment and water samples collected from the Persian Gulf and enclosed industrial areas by ZOLGHARNEIN et al. (2007). All the isolated bacteria were identified by 16S rRNA gene sequencing. Using the modified alkaline lysate method, isolated bacteria were tested for the presence of plasmids. The study revealed that the plasmid occurrence frequency in the bacteria resistant to heavy metal was more as in the ordinary bacteria. The study also demonstrated that about 66% of isolated bacteria carried large (38-62 kb) and/or small sized (4- >2 kb) plasmids. The highest plasmid incidence (84.6%) was detected from industrial wastewater bacteria. A slightly higher incidence of plasmids occurred in bacteria isolated from marine sediments (55.5%) compared to that of the marine water (53.8%). The findings suggested that plasmids are highly ubiquitous and predominant in most heavy metal resistant bacteria. Removal of lead and cadmium from solution by some of these bacteria was very efficient, approximately 120 mg/g dry weight as high as 90%. The isolates tested, presented distinct uptake capacities and the best results were obtained for Delftia tsuruhatensis and Pseudomonas AU3411 respectively.
FAROOQ et al. (2008) assessed the Pb, Cu, Cr, Zn and Cd contents in different leafy vegetables i.e. cabbage, cauliflower, coriander, lettuce, radish and spinach grown in a field irrigated with effluent in the surrounding area of an industries of Faisalabad, Pakistan by the use of AAS. The concentrations of Pb, Cu, Cr, Zn and Cd in the leaves, stems and roots of spinach, coriander, lettuce, radish, cabbage and cauliflower were found to be from 1.1331 to 2.652 mg/kg, from 1.313 to 2.161 mg/kg, from 1.121 to 2.254 mg/kg; from 0.252 to 0.923 mg/kg, from 0.161-0.855 mg/kg, 0.221 to 0.931 mg/kg; 0.217-0.546 mg/kg, from0.376 to 0.495 mg/kg, from 0.338-0.511 mg/kg; from 0.461to 1.893 mg/kg, 0.361-0.874 mg/kg, 0.442 to 1.637 mg/kg; from 0.033 to 0.073 mg/kg, from 0.017 to 0.061 mg/kg, from 0.011 to 0.052 mg/kg on the basis of dry matter, respectively. The Pb, Cu, Cr, Zn and Cd contents were less than the FAO/WHO (Expert Committee on Food Additives) recommended highest acceptable levels. Spinach, cabbage, cauliflower, radish and coriander's leaves accumulated higher concentrations of Pb (2.652 mg kg-1), Cu (0.923 mg kg1), Cr (0.546 mg kg-1), Zn (1.893 mg kg-1) and Cd (0.073 mg kg-1) in comparison to other parts of all vegetable.
REHMAN et al. (2008) reported the concentration of metals that are necessary and toxic (Pb, As, Ca, Cu, Fe, Na, K and Zn) from the analysis through atomic absorption spectroscopy and flame emission spectroscopy in the wastewater of Pakistan's three major industrial estates that is, Industrial Estate No. one Peshawar, Small Industrial Estate No. 2 Gujranwala, Industrial Estate Hattar Haripur, and in Warsak Canal. They observed high Pb levels were released from industries. The range of all samples Pb concentration was from 0.04 to 0.942 ppm.
JAYSANKAR et al. (2008) analyzed many marine bacteria that were highly mercury resistant had the ability to grow at 25 ppm (mg/L) or even higher mercury concentrations in their study to assess the ability of those bacteria to detoxify Pb and Cd. It was showed by the results that detoxification ability not only comprised by Hg, but also Pb and Cd. Those identified bacteria belong to Alcaligenes faecalis (seven strains), Bacillus pumilus (three strains), Bacillus sp. (one strain), Brevibacterium iodinium (one strain) and Pseudomonas aeruginosa (one strain) and by biochemical and 16S rRNA gene sequence analyses. Detoxification of heavy metals was done through putative entrapment within the extracellular polymeric substance (Pb, Cd and Hg) the same as revealed by the SEM (Scanning Electron Microscopy), volatilization (for mercury) and EDS (energy dispersive X-ray spectroscopy), and/or precipitation such as sulfide for lead. Identified bacteria eliminated over 98% of lead (Pb) for 96 hours and 70% of cadmium (Cd) for 72 hours from growth media, had 100 ppm as an initializing metal concentration. The efficiency of detoxification of identified bacteria for lead, cadmium and mercury exposed better probability for application of heavy metals bioremediation.
JIANG et al. (2008) isolated a bacterial isolate from soil polluted with heavy metals that was resistant to heavy metal as well as based on the 16S rDNA gene sequence analysis, identified as Burkholderia sp. J62. They investigated antibiotic along with heavy metal resistance, isolate's heavy metal solubilization. Isolates were evaluated in the pot experiment for lead (Pb) and cadmium (Cd), plants uptakes through heavy metal polluted soils and for promoting plant growth. They found that isolate exhibited the characteristics of variable antibiotic and heavy metal resistance. In solution culture and in soils, an increase in the solubalization of bacteria for Pb and Cd had been showed from AAS analysis. The isolate originated siderophore, indole acetic acid and 1-aminocyclopropane-1-carboxylate deaminase. Isolates also solubilized inorganic phosphate. The tomato plants and maize crop biomass was establish to increase significantly (p<0.05) by inoculation within the isolate. The contents of lead (Pb) and cadmium (Cd) varied from 38%-192% and from 5%-191% in growth of inoculated plants in the soil polluted with heavy metal comparably to the un-inoculated control. It was showed by the results that solubilization of heavy metal and bacteria that promote plant growth were significant for the growth of plants and uptake of heavy metal which may provide recent microbial improved phytoremediation of soil contaminated with metal.
KANWAL et al. (2008) conducted a study of a period of one year (2006-7) by visiting at DHQ Hospital Faisalabad and considered the patients from industrial area coming to the hospitals. For this study, selected patients were those that were diagnosed with lead toxicity clinical symptoms. The demographic features of the patients concerning their age, gender, marital status, family size, education, income, duration on job, working place and nature of work were considered. The studies data was categorical nature and this measures the associations along with environmental exposure with lead toxicity and studied contributory risk factors i.e., cholesterol level, Hb level (anemia) causing ischemic heart disease (IHD).
SHENG et al. (2008) isolated and characterized two endophytic bacteria that were resistant to Pb (lead) from the rape roots which were grown in the soil polluted with heavy metal. The experiment to examine the ability of two growth promoting isolates as well as uptake of lead (Pb) from rape through the soil contaminated with lead. The two identified isolates were Microbacterium sp. G16 and Pseudomonas fluorescens G10 which were determined on the 16S rDNA gene sequence analysis basis. Various antibiotic and heavy metal resistance showed by isolates G10 and G16. In solution and in lead contaminated soil, increased water soluble lead was exhibited by those strains. In comparison to the control plants, inoculated rape seedlings elongation was established by elongation assays of roots. Siderophores, indole acetic acid and1-aminocyclopropane-1-carboxylate deaminase were produced from Microbacterium sp. In comparison to the control, there was an increase in biomass production and total lead uptake in the plants induced by bacteria. The two isolates might be colonized rape rhizosphere as well as root interior after the inoculation of roots.
RAJBHANSI (2008) isolated10 heavy metal resistant bacteria from oxidation ditch of waste water treatment plant of Bagmati Area Sewerage Project. Those consisted of chromium resistant Staphylococcus spp, Klebsiella spp, Escherichia coli; cadmium resistant Acinetobacter spp, Citrobacter spp, , Flavobacterium spp; nickel resistant Bacillus spp, Staphylococcus spp; copper resistant Pseudomonas spp; and cobalt resistant Methylobacterium spp. Each isolate highly resistant to heavy metals with MIC (Minimum Inhibitor Concentration) ranged from 150 to 500 Î¼g/ml of heavy metal. Six resistant isolates exhibited multiple tolerances to heavy metals. Antibiotic resistance was shown by all of the 10 isolates out of which 10% were resistant to single antibiotic and 90% were resistant to multi antibiotic. Highest tolerance by microbes showed from heavy metal tolerance test to chromium and minimum tolerance to nickel in mixed liquor sample of oxidation ditch.
WAKAWA et al. (2008) collected surface water samples from River Challawa, Nigeria, in order to understand bioavailability of heavy metals in water to find out the industrial waste water effect on river water. They analyzed limited amount of heavy metals (Cd, Cr, Pb and Zn) in water by using atomic absorption spectrophotometer. They also analyzed water samples for physico-chemical properties. The results evaluated that all physico-chemical parameters were determined: Total Dissolved Solids (TDS), Total Solids (TS), pH, Total Suspended Solids (TSS), Chloride (Cl-), Sulphate (SO4), Temperature, Phosphate (PO4) with exception of DO, BOD, COD and EC were within the recommended standard values for these contents in drinking water. The results taken from this study showed the pollution capabilities of the river Challawa's surface waters, attributable to high Pb, Cd and Cr levels measured. Generally, high Pb and Zn levels were observed at control site, which showed that other sources than industrial effluents could be responsible. Then it was suggested that more stringent methods of waste water management should be adopted to reduce further addition into the area.
EL-HENDAWY et al. (2009) studied the isolation of bacteria resistant to heavy metals. They obtained bacterial isolate from a heavy metal receiving site from the steel and iron factory; a main factory at El-tebeen in south He lwan. API system identified the isolate as Vibrio alginolyticus. The highest tolerated concentration was 2.5 mM for Pb, 2.5 mM for Cd, 4 mM for Cu and 3.5 mM for Zn. Transmission electron micrograph of Vibrio alginolyticus mature in broth contained a combination of 4 heavy metals which showed heavy metals bioaccumulation on the cell wall of bacteria. Simultaneously, in culture supernatant, overall heavy metal level reduction was less and the %age reduction was 40% for Pb, 31% for Cu, 20% for Cd and 45%for Zn. For all metals (Pb, Cu and Zn), the reduction occurred at 30 °C after the incubation of four hours but Cd needed the incubation of twenty four hours to attain highest reduction. That strain might be used to speed up the in situ site bioremediation polluted with mixed metals.
HE et al. (2009) investigated two strains Bacillus sp. RJ16 and Pseudomonas sp. RJ10, that were resistant to Cd (cadmium) for their impact on the soil Pb and Cd solubilization and plant growth promotion and lead and cadmium uptakes of a cadmium hyper accumulator tomato. An increase in the CaCl2-extractable Pb (by 67%-93%) and Cd (by 58%-104%) was observed in the inoculated soil polluted with heavy metal in comparison to the un-inoculated control. Siderophore, indole acetic acid and 1-aminocyclopropane-1-carboxylate deaminase were produced by those isolated bacteria. They conducted assess of elongation of root on tomato in gnotobiotic situation established an increase in the elongation of root of inoculated tomato seedlings comparably to the control plants. They observed that an increase in the contents of Pb and Cd of tissues that were above the ground varied from 73-79% and 92% to 113% within the inoculated plants growing in the soil contaminated with heavy metal in comparison to the un-inoculated control, correspondingly. It was revealed by the results that the bacteria might be exploited for bacteria, improved phytoextraction of Pb- and Cd- contaminated soils.
KABIR et al., (2009) studied the effect of green house in innate environmental circumstances with and without ions of phyto toxic metal at 5 Î¼mol/L, 10 Î¼mol/L, 15 Î¼mol/L, 20 Î¼mol/L and 25 Î¼mol/L determined lead effects shoot, root, length of seedling, leave numbers, area of leaf, plant circumference, dry weight of seedling and ratio of root/shoot along with leaf area of Thespesia populnea L. Pb treatments produced major effect on T. populnea growth and development by reducing considerably (P<0.05) for above parameters. At 5-25 Î¼mol/L, Significant effects of lead treatment were observed on root length side and seedling. Similarly, at 10-25 Î¼mol/L, significant effects were produced by lead treatment on length of shoot, leaves number and area of leaf area with comparison to control. A considerable (P<0.05) decrease in plant circumference and dry weight of seedling of T. populnea was examined with rising lead concentrations from 5 Î¼mol/L to 25 Î¼mol/L when compared with control. Tolerance in the seedlings of T. populnea at 25 Î¼mol/L of treatment with lead was least when compared to remained treatments.
MALAKOOTIAN et al. (2009) studied in April 2008, the capability of light extended clay aggregate to reduce Pb and C in the wastewater of paint industry at various levels of absorbent, time duration and pH. They studied the removal of Pb and Cd from the wastewater of paint industry in batch reactors. The calculations for Pb and Cd had been done through non-flame AAS and for wastewater and simple water examination they adopted methods of test from standard method's 19th. Eddition. Various amounts of Leca (from 1g/L to 10 g/L) were investigated. The absorbed amount of Pb and Cd exposure to Leca increased from 1.41 mg/g to 3 mg/g and 0.22mg/g to 0.75mg/g, respectively. For Pb (lead) at 7 pH, the highest eliminating efficiency was 93.75 % and contact to 10 g/L of Leca, whereas for Cd (cadmium), that efficiency was approximately 89.7 % under the same condition. It was indicated by the results that accessible and low cost absorbant was Leca to reduce Pb and Cd from industrial effluents.
RANI et al. (2009) isolated heavy metal resistant bacteria from the effluents samples of an electroplating industry which used Pb, Cd and Cu for plating. The study was aimed to evaluate the isolates applicability which was characterized for the removal of heavy metal from the wastewater of industries. An analysis of the samples physico-chemical properties was performed. Optimum conditions of pH, concentration of biomass and concentration of heavy metal were evaluated for the growth of microbes on biosorbents and correlated with the removal of heavy metal. The process of biosorption conceded out in dead and immobilized bacterial strains and applied through the observed optimal conditions. The immobilized cells biosorption of Micrococcus sp. For lead was 84.27%, Pseudomonas sp. For cadmium was 90.4 1%and Bacillus sp. For copper was 69.34%, while the Micrococcus sp. dead cells accounts almost 79.22% for lead, Bacillus sp. was 44.73% for copper and Pseudomonas sp. was 86.66% for cadmium. It was revealed by the results that all the immobilized strains had potential application for lead, cadmium and copper removal from the wastewater of industries rather than the dead cells of bacteria.
SMITH in 2009 examined heavy metal's effects in manure and soil as a base with significant pressure on agricultural production for attaining a maintained balance between various agricultural policy aims and practical. In source segregated and green waste compost, total concentrations of heavy metals were less than UK PAS100 permissible levels and physically separated materials conformed metal permissible limits in UK PAS100. Zn and Pb were present in the great concentrations in municipal solid waste (MSW) compost. Lead (Pb) was the most restrictive constituent in domestic gardens, physically segregated compost but lead (Pb) contents were less than the safe limits that had no adverse effect on human health. Heavy metals had a high affinity for binding showed by composted residues resulting from green waste and municipal solid waste. Strongly bounded element was lead (Pb) while the weakest on was nickel (Ni) along with cadmium (Cd), copper (Cu) and zinc (Zn) which showed the characteristics of intermediate sorption. It was revealed the compost properties of strong metal sorption produced from sewage sludge or municipal solid waste had significant benefits for urban and industrial soils contaminated with heavy metals remediation. The soil availability based on chemical association's nature within the soil matrix and metal along with organic residues, the compost's elemental concentration, soil's pH values, plants capability to sustain the particular element uptake. When application of compost had been finished, no proof was found for the metal release increment in the form of organic matter that degraded in the soil. It was concluded and revealed by the scientific evidences that conservative and pragmatic levels on compost heavy metals could be set to enhance composted residual recycling and measures of contaminant elimination which also protected the environment and soil from adverse effects produced through heavy metals long term accumulation in soil.
AHMAD AND GHONI (2010) estimated the Pb, Cd, Cr, Cu, Fe, Ni and Zn concentrations in vegetables and soils within Bangladesh's some industrial area. In contaminated irrigation water, metal contents were found in the order of Fe > Cu > Zn > Cr > Pb > Ni > Cd, and almost same pattern Fe > Zn > Ni > Cr > Pb > Cu > Cd was experienced in the soils of arable. Observed levels of metal in various sources were compared against SEPA, WHO and other authors established permissible levels. In soil, t contents of cadmium and the average Cd, Cu and Fe concentration in irrigation water was greatly higher against the recommended level. Heavy metal accumulation in vegetables was less than the maximum tolerated level recommended by the Joint FAO/WHO Expert Committee on Food Additives (1999), with the cadmium exception which showed greater content. Metal uptake and translocation pattern for all the examined elements to vegetables edible parts from soil were rather important to note.
HYNNINEN et al. (2010) described a lead (Pb) resistance system between P-type ATPases and CBA transporters. They observed lead resistant TRABCD cluster of gene from CH34 (Cupriavidus metallidurans) which showed that PbrA exported zinc (Zn2+), cadmium (Cd2+)and lead (Pb2+) were the major carrier components of the operon while the PbrB was 2nd component of the operon shown a high resistance against lead because it acted as phosphatase. By utilizing the P-type ATPase, the innovative lead (Pb) resistance system removed lead (Pb2+) ions and in periplasm, an inorganic phosphate produced for lead (Pb) sequestration. Innovative mechanism of lead sequestration was described for the first time in this study. This study also focused on the lead resistant (pbr) operon. This research indicated that P-type ATPase and phosphate producing genes were present different bacterial isolates, especially lead toxicity remediation could be done by sequestration and active efflux processes and it could be a widespread mechanism that was resistant to lead. Two transporter were induced by lead (Pb2+), mercury (Hg2+), nickle (Ni2+), copper (Co2+), zinc (Zn2+) and cadmium (Cd2+), while a 3rd transporter was induced to Zn2+ specifically.
GHANI (2010) examined two maize varieties that were Neelam and Desi and exposed them to various lead concentrations [0 ppm, 10 ppm, 20 ppm and 30 ppm Pb(NO3)2.4H2O] in earthen pots for 14 days. Significant root growth inhibition would result when he exposed those maize varieties to excess Pb while shoot growth remained less affected. It was indicated by the analysis results of chlorophyll that the highly toxic lead level affected photochemical efficiency in Neelam, whereas un considerable effects were observed in Desi. Lead accumulation was associated with obtained results. It was indicated by the present study results that the roots of Desi had higher capacity of Pb accumulation and withstands excess concentration of Pb. Hence, Desi was more lead toxicity tolerant in comparison to Neelam that was institute to be vulnerable variety.
SA'IDI (2010) studied the negative effects of heavy metals on biological wastewater treatment plant including microorganisms that were known as harmful pollutants in waste water. Few heavy metals for example Pb (lead), at minimum levels were poisonous for microorganisms. It was observed that, according to rule, heavy metal had a harmful effect on the water microorganism's growth because it can greatly reduce their numbers. He explained that microorganism's number based on the heavy metals concentration and total contents, as well as conditioned by various other factors, pH, moisture, temperature, exchange capacity, organic matter's quality and quantity, organic matter rich with carbohydrate and nutrient availability. Microbial population structure had been changed and effected their composition of species and diversity, activity and reproduction of every microorganism. Heavy metals high levels in wastewater become a reason of significant reduction in the bacterial numbers of biological system.
SINGH et al. (2010) isolated the 8 Pseudomonas sp that were resistant to heavy metal t from industrial effluents sewage from treatment plant of wastewater of Paonta Sahib H.P. India, for cadmium, chromium, copper and nickel. Heavy metals high resistance with MIC (minimum inhibitory concentration) for heavy metals ranged (50 - 350ppb) was exhibited by all the isolates. Different tolerances to heavy metal were exhibited by all the isolates and were multi antibiotic resistant. Pseudomonas sp (Ps-6) highest microbial tolerance Cu (300 ppb) and least to Cr (60 ppb) were indicated through heavy metal tolerance test.
LIN AND HARICHUND (2011) observed the bioflocculants that were potential flocculating agents in the treatment of industrial wastewater effluents produced by Herbaspirillium sp. CH7, Paenibacillus sp. CH11, Bacillus sp. CH15 and Halomonas sp. Increases in bioflocculant production were obtained by manipulation of the media composition that was up to 250%. Bioflocculants production was enhanced by increases in peptone and glycerol contents, up to 2 and 3%, respectively. All isolates favored higher yeast extract content for bioflocculant production except of Herbaspirillium sp. CH7,. Physicochemical analysis showed that most of bioflocculants produced, seemed to contain high protein content, then carbohydrate. All bioflocculants consisted of same uronic acid and hexosamine contents in the range of 0.0054 to 0.0068 mM and 0.0115 to 0.0150 mM, respectively. Purified bioflocculants contained higher flocculating activities (up to 14-fold increases) produced under optimized conditions in comparison to those under the control conditions except Herbaspirillium sp. CH7. A significant increase in the removal percentages of Pb+2, Zn+2 and Hg+2 with the optimal dosage of 1 to10 ppm was the result of a decrease in bioflocculant concentration from 10000 ppm to 1 ppm. They studied that bioflocculants removed Cd+2 effectively only at 10000 ppm not at the lower concentrations. The capacity of bioflocculant of Cd+2-removing could be further enhanced by an increase in temperature. The pH requirement for maximum flocculating activity appeared to be different for various strains of microorganisms.
LOKHANDE et al. (2011) conducted a study for the pollution assessment because of poisonous heavy metals within the industrial waste water effluents collected from Taloja industrial belt of Mumbai. The study showed that dyes, paints, pharmaceutical and textile industries were some of the major industries contributing to the heavy metal pollutants in the surrounding aquatic environment. It was noticed that paint manufacturing industries are the major contributors of toxic Cr, Zn and Pb amounting to 35.2, 33.1, and 31.4 ppm respectively. It was also observed that major contribution of Cu (33.3 ppm) was from dyes manufacturing units, while maximum Fe concentration of 12.8 ppm was found in effluent samples released from textile industries. The concentration of Cd and Ni was found highest in effluent samples collected from pharmaceutical industries amounting to 35.8 and 33.6ppm, respectively. The overall results showed high concentration of sample effluent's poisonous heavy metals collected from various industries. Those industrial effluents would pollute the nearby water bodies affecting the growth of vegetation and aquatic life. These toxic heavy metals when released in aquatic environment would enter the food chain through biomagnification causing various health problems in humans. The results of this study pointed out the required implementation of common objectives, attuned policies and programmes designed to improve the treatment method for industrial waste water.
MURTHY et al. (2011) carried out a study that indicated that the metallothionein concentration increased in Bacillus cereus treated with different concentrations of lead with increasing lead concentration. The B. cereus protein samples treated with different lead concentrations were isolated and electrophoresed on SDS-PAGE and 2-D gels. It was revealed by the study of gels that in case of B. cereus a thick protein band appeared around 14.3KD treated with lead disparate the control samples.
NANDA et al. (2011) studied the role of bacteria in eliminating the heavy metals present in the industrial effluent. They selected five effluent samples out of nine were for the study due to high content of heavy metals. The heavy metals Hg and Cu were removed by Bacillus sp. The average Hg and Cu decrease was 45% and 62% was observed, respectively. The heavy metals Cd, As and Co were eliminated by Pseudomonas sp. The average Cd, As and Co reduction was 56%, 34% and 53% respectively. Staphylococcus sp. removed the heavy metals Cd and Cu and the average Cd reduction was 44% and observed average Cu reduction was 34%.
WARANUSANTIGUL et al. (2011) investigated the biosorption of lead by Eucalyptus camaldulensis, a woody plant and ability of rhizospheric isolate in plant growth promotion in water excess conditions. 3 lead resistant isolates were identified from rhizosphere of E. camaldulensis, that was grown in BoNgam lead mines 's soil contaminated with lead, Thailand. Based on partial 16S rRNA gene sequence analysis, Bacillus fusiformis sp. (BN-4), Microbacterium paraoxydans sp. (BN-2) and Ochrobactrum intermedium, sp. (BN-3) were the identified species. O. intermedium sp. (BN-3) exhibited high resistant to lead and to also highly tolerant to zinc and cadmium. Due to the presence of lead, O. intermedium sp. (BN-3)'s cells membrane exhibited a decrease in fluidity but undissolved fatty acids level increased. The biomass was increased by the inoculation of O. intermedium sp. (BN-3) significantly and in hydroponic conditions leads concentration accumulated by E. camaldulensis, woody plant as compared to control that was not inoculated. The results showed the potential efficiency of O. intermedium sp. (BN-3) and other isolated bacteria in phytoremediation had been improved.
AUCOTT AND CALDARELLI (2011) measured the quantity and evaluated the lead fate and form which enters the environment from wheel weights, and to estimate the potential exposure that lead might be represented in comparison to the evaluated and measured lead inputs into the environment. Lead was founded more or less 12 t/yr in wheel weights form which was dispersed on the roadways of New Jersey and only forty kg of that amount enters into the environment in small particles form which were resulted from grinding action and traffic pollution. It was indicated that, comparative to other resources, lead dispersed amount into the environment in small particles forms from wheel weights. Additionally, the discharged amount of lead (Pb) through wheel weights seemed to be decreased due to state level legislation, voluntary phase outlets of manufacturers as well as new trends in wheel technology.
ZHANG et al. (2011) isolated 49 Pb resistant endophytic bacterial strains from Commelina communis, a metal resistant plants, grown-up on zinc (Zn) and lead (Pb) mine shadowing, 7 out of which was (ACC) 1-aminocyclopropane-1-carboxylate deaminase produced an endophytic bacterial strains were founded initially, then according to the heavy metals resistance, (IAA) indole-3-acetic acid, production of ACC deaminase and siderophores were characterized. Two strains that showed (ACC) 1-aminocyclopropane-1-carboxylate deaminase production were observed and evaluated for enhancement of the growth of plant and lead (Pb) uptake in (quartz) sand consisting 0 and 100 mg/ kg Pb in pot experiments. The 7 lead resistant isolates and endophytic bacterial isolates producing 1-aminocyclopropane-1-carboxylate (ACC) deaminase were observed to show various resistance characteristics against heavy metal and exhibited various limits of 1-aminocyclopropane-1-carboxylate (ACC) deaminase production (ranged from 12.8 Î¼M Î±-KB /mg/h to 121 Î¼M Î±-KB/ mg/h). Out of 7 isolates, six isolated bacterial strains showed indole acetic acid production, while five strains exhibited the production of siderophores. The rape plants grown in experiments in sand quartz consisting 100 mg /kg of lead, inoculated with the bacterial isolates caused an increase in dry weights of tissues above the ground (ranged from 39% - 71%) while roots (ranged from 35% - 123%) as compared to controls. Lead concentration was high in tissues above the ground level cultivated in 100 mg/ kg of lead polluted substrates differed from 58% - 62% in uncontrolled plants as compared to the control plants.
NASIR et al. (2012) planned their study to investigate the quality status of the city effluents from Gujranwala; a hub of several industries in Pakistan. They conducted a field survey to locate the sampling area from where effluent samples might be collected from different industrial wastewater discharge outlets or locations. They determined the water quality parameters at different points. The observed values of COD, BOD, TSS, TDS, dissolved oxygen (DO), pH, turbidity, electric conductivity (EC), Carbonates (CO3-1) and Bicarbonates (HCO3-1) were different for the various industries as