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Jianshe L et al., 3 (2010) performed the heavy metal resistance by two bacteria strains isolated from a copper mine tailing in china. Two highly heavy metal resistance indigenous bacterial strains, DX-T3-01 and DX-T3-03, were isolated from the biggest tailing in Asia-Dexing copper mine 4# tailing. The strain DX-T3-01 exhibited high tolerance to cadmium. The strain DX-T3-03 was highly resistant to zinc. The morphological, physiological and biochemical characteristics of the two strains were examined by scanning electron microscope (SEM) and BIOLOG. The strains showed different metabolic patterns of carbon sources. The strain DX-T3-03 had a larger range of antibiotic resistance than DX-T3-01. On the basis of 16S rDNA sequencing, the two strains were identified as Ralstonia pickettii strain DX-T3-01 and Sphingomonas sp. Strain DX-T3-03, respectively.
Ramaiah N et al., 4 (2003) performed the Unusual rise in mercury resistant bacteria in coastal environs. High counds of MRB (96% of CFU) were recorded from samples collected from the polluted zones of Mumbai, the MRB capable of growth on sea water nutrient agar with 10 ppm Hg were most samples collected from locations with low or no pollution effects. Aerobic heterotrophic bacteria isolates capable of growth at 50 ppm Hg. Such MRB grew in much higher concentration of many toxic xenobiotics than the Hg sensitive ones is reported.
Jaysankar D et al., 5 (2008) performed the detoxification of toxic heavy metals by marine bacteria highly resistant to mercury. Marine bacteria highly resistant to mercury (BHRM) capable of growing at 25 ppm (mg L-1) or higher concentration of mercury were tested. The results indicate that their potential of detoxification not only of Hg, but also Cd and Pb. Through biochemical and 16S rRNA gene sequence analyses, these bacteria were identified to belong to Alcaligenes faecalis (seven isolates), Bacillus pumilus (three isolates), Bacillus sp (one isolate), Pseudomonas aeruginosa ( one isolate) Brevibacterium iodinium (one isolate). The mechanism of heavy metal detoxification were through volatilization, putative entrapment in the extracellular polymeric substance as revealed by the scanning electron microscopy and energy dispersive x-ray spectroscopy and/or precipitation as sulpfide (for Pb). These bacteria removed over 70% of Cd and 98% of Pb within 72 and 96 h respectively from growth medium that had initial metal concentrations of 100 ppm.
Jaysankar D et al., 6 (2003) performed the Tolerance to various toxicants by marine bacteria highly resistant to mercury. Bacteria highly resistant to mercury isolated from sea water and sediment samples were tested for growth in the presence of different heavy metals, pesticides, phenol, formaldehyde, formic acid and trichloroethane were investigated for their potential for growth in the presence of a variety of toxic xenobiotics. The MRB were found to belong to Pseudomonas, Proteus, Xanthomonas, Altermonas, Aeromonas and Enterobacteriaceae. All the bacterial strains were tolerant to mercury were capable of growth at far higher concentration of 50 ppm of mercury, they are ability to grow in the presence of toxic xenobiotics, either singly or in combination. Those bacteria incapable of growth in media containing 5 ppm Hg.
Vajiheh K et al., 7 (2003) performed the Antimicrobial, heavy metal resistance and plasmid profile of coliforms isolated from nosocomial infections in a hospital in Isfahan, Iran. Fifteen of the 25 isolates from nosocomial infections were identified as E.Coli, and remaining as Kelebsiella Pneumoniae. 72% of strains isolated from nosocominal infections possess multiple resistance to antibiotics compared to 45% of strains from healthy human faeces. The difference between MIC values of strains from clinical cases and from faeces for four heavy metals. Most strains isolated from hospital were more tolerant to heavy metal than those from healthy persons. Multidrug-resistance coliforms as a potential cause of nosocomial infection in this region is reported.
Clausen CA et al., 8 (2000) Isolated metal-tolerant bacteria capable of removing copper, chromium, and arsenic from treated wood. Sampling 8 environments with elevated levels of copper, chromium, and arsenic resulted in the isolation of 28 bacteria with the capability of releasing one or more of the components from chromate copper arsenate-treated wood. The isolates represent 13 species of 8 different genera of soil inhabiting bacteria. The isolates, Acinetobactor Calcoaceticus FN02, Aureobacterium esteroaromaticum VV03, Klebsiella oxytoca CC08, were able to release 98% of the chromium. Bacillus licheniformis CC01 released the highest percentage of copper, 93%, from treated wood. 11 isolates, including Bacillus licheniformis CC01, and Acinetobacter calcoaceticus FN 02, released 44% to 48% of the arsenic.
Colwell RR et al., 9 (1975) performed Effects of mercuric chloride on growth and morphology of selected strains of Mercuric- Resistant Bacteria. Cultures which adapt to growth in the presence of HgCl2 exhibit extensive morphological abnormalities. A detailed analysis of the adaptation process and the resulting effects on morphology was performed on a Enterobacter sp. The growth commenced only at a specific threshold concentration of Hg2+.
Colwell RR et al., 11 (1974) performed the Mercury-Resistant Bacteria and Petroleum Degradation. The concentration of mercury in water and sediment and in the oil extracted from water and sediment was determined for samples collected in Colgate Creek. The concentration of mercury in the oil was 4,000 times higher than in sediment and 300,000 times higher than in water samples. The mercury-resistant bacterial populations of the samples studied have been shown to degrade oil.
Arif A et al., 12 (2010) performed isolation, identification and PCR amplification of merA gene from highly mercury polluted Yamuna river. Mercury resistant E. Coli strains have been isolated from different mercury polluted sites of India and their MIC levels were determined. The location of mer operon was determined by transforming the isolated plasmids into mercury sensitive host DH5α cells. Plasmid isolated from transformed DH5α cells were also analyzed and compared with the plasmid profile of wild-type strains.
Agnes R et al., 13 (2005) Identified rcnA (yohM), a Nickel and Cobalt Resistant Gene in E.Coli. yohM encodes a membrane bound polypeptide conferring increased Nickel and Cobalt resistant in E. Coli. YohM was specifically induced by nickel or cobalt but not by cadmium, zinc or copper. Mutation of yohM increased the accumulation of nickel inside the cell, whereas cells harboring yohM in multicopy displayed reduced intracellular nickel content.
OLSON H et al., 14 (1985) performed effect of metal-rich sewage sludge application on the bacterial communities of grasslands. Long term application of heavy metal laden sewage sludge on the total heterotrophic aerobic and the cadmium resistant soil bacterial communities was studied. Gram-positive bacteria was completely absent from resistant communities. Cd-resistant communities isolated from long-term sludge amended soils were more diverse than the resistant communities from a control sample, suggesting that adaptation to cd as a stressor had occurred in the presence of sludge constituents. This higher diversity was attributed to cd resistance in pseudomonads and gram negative fermenters.
Colwell RR et al., 10 (1977) performed antibiotic resistance patterns of Metal-Tolerant bacteria isolated from an Estuary. Estuarine bacteria isolated on metal-containing media were also found to be antibiotic resistance; ampicillin and chloramphenicol were the antibiotics to which resistance was most common.
Mathivanan K et al., 15 (2010) performed bacterial resistant to Mercury pollution through genetic transformation. The contaminated soil samples were collected from around the BHEL, Tiruchirapalli. The isolation of bacteria from soil sample was done by nutrient agar plate method. A total of 15 colonies were isolated from the polluted soil sample. Among them colony no.12 showed better growth in high HgCl2 concentration, indicating the mercury resisting capacity of S. aureus identified by morphological and biochemical tests. Out of 15 colonies, seventh colony show no growth which was sensitive to mercury. The plasmid DNA from S. aureus was isolated and transformed into mercury sensitive E.coli. The sensitive E.coli get mercury resistant capacity was conforrned by agarose gel electrophoresis.
Hatha AAM et al., 16 (2006) performed antimicrobial activity of some of the south Indian spices against serotypes of E.Coli, Salmonella, Listeria monocytogenes and Aeromonas hydrophila. Antibacterial activity of extracts of garlic, nutmeg, ginger, onion and pepper has been evaluated against 20 different serogroups of E.coli, 8 serotypes of salmonella, Listeria monocytogenes, Aeromonas hydrophila. Garlic extract showed excellent antibacterial activity against all test organism except L. monocytogenes. Nutmeg showed good anti-listerial activity, although activity against E.coli and salmonella were serotype dependent. Both garlic and nutmeg extract against A. hydrophila . extracts of onion and pepper did not show any antibacterial activity against the test organisms.
Hossein Z et al., 17 (2007) detected plasmid in heavy metal resistance bacteria isolated from the Persian Gulf and enclosed industrial areas. Several heavy metal resistant bacterial strains were isolated from sediment and water samples collected from the Persian Gulf and enclosed industrials areas. All the isolated bacteria were identified by 16S rRNA gene sequencing. Isolated bacteria were tested for the presence of plasmids using the modified alkaline lysate method. The study revealed that the frequency of the occurrence of plasmids in heavy metal resistant bacteria was more than that in the common bacteria. The study also demonstrated that about 66% of isolated bacteria carried large of small sized plasmid. The highest plasmid incidence (84.6%) was detected from industrial wastewater bacteria. Removal of lead and cadmium from solution by some of these bacteria was very efficient, approximately 120mg/g dry weight as high as 90%.
Mirzaei N et al., 18 (2008) Isolated Mercury Resistant Bacteria from Kor River, Iran. The samples were collected from 4 stations throughout the kor river in 4 seasons. Amount of total mercury in the samples was determined using cold vapor atomic absorption spectrophotometry. The response of bacterial communities to toxic effects was Hg was monitored by enumerating the number of bacteria on agar containing 10 mg L-1 HgCl2 and without Mercury (II). Isolation of mercury resistant bacteria was performed using primary enrichment culture method and directly plating on agar containing 10mg L-1 HgCl2 Hg (II). Total viable counts ranged from 6.5- 106 to 2.2- 107 cfu g-1 in different stations. Pseudomonas sp., E.coli, Serratia marcescens, etc. was identified as mercury resistant bacteria.
Roberts MC et al., 19 (2008) performed Dental Amalgam and Antibiotic- and/or Mercury-resistant Bacteria. Samples were collected at baseline, 3-6 months after the initial dental treatment, and annually for 7 years of follow -up. The study provided no evidence that amalgam fillings on posterior teeth influenced the level of antibiotic or mercury resistant oral or urinary bacteria as detected by culture.
Edward Raja C et al., 20 (2009) performed Isolation, identification and characterization of heavy metal resistant bacteria from sewage. The bacteria was isolated from sewage water collected in the around Madurai district. Initially 300 isolates were screened from sewage water. The four isolates were selected based on high level of heavy metal and antibiotic resistances. The sewage isolates showed optimum growth at 30oC and pH 7.0. the identified isolates were resistant to Cd, Ni, Pb, As, Cr, Hg. The MIC was determined in solid media. The isolates resistant to antibiotics were reported.
Chandrasekaran N et al., 22 (2010) Identified high chromium tolerant bacterial strains from palar river basin: impact of tannery pollution. Chromium tolerant strains were isolated from contaminated sediments, water and effluents of various tanneries. The minimum and maximum concentration of chromium sediments was in the range of 47.4 and 682.4 mg L-1, with an wide range of 306.285mgL-1 in the study area. These bacterial isolates were also checked for their resistance to other heavy metals. 80% of the isolates showed resistance to Ni, Pb, Zn. Fe at 100ppm level 45% of isolates showed resistance to Cd.
Mahipal S et al., 22 (2010) Performed plasmid DNA transformation in Escherichia Coli: Effect of Heat Shock Temperature, Duration, and Cold Incubation of CaCl2 Treated Cells.Escherichia coli strain DH5α -T1R with plasmid pUC19 were optimized. Of the four different heat shock temperatures (32°C, 37°C, 42°C and 47°C) studied, 42°C treatment exhibited maximum efficiency of transformation as revealed by ampicillin-resistant colonies appearing on LB Agar ampicillin plates. Of the five different heat shock exposure times, a pulse of 30 second duration combined with 42°C heat shock temperature exhibited maximum efficiency. It was observed that although transformation of CaCl2 treated cells occurs even before heat shock treatment, the efficiency was ~15 fold higher after heat shock. When the cells were further incubated on ice (after heat shock) for 10 min, the transformation efficiency increased by 24 fold compared to no heat shock and 1.6 fold compared to heat shock treatment. Results also suggest that post heat shock cold incubation step is also an important factor and enhances transformation of E. coli significantly.