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The study of algae is called phycology ( South, G.R., & Whittick, A., 1987). It belongs to kingdom of plant and dominated the group of organism which has since the earliest times. It can be found in both prokaryote and eukaryote. There is evident the existing of the prokaryote algae is when the fossil fuels are recorded and proved that the first photosynthetic cellular plants.
Algae have played only a minor role as disease agents, but that are significant agents of a variety of toxic and nuisance problems. They have the important niches as a primary producer and over the time have develops the formation of calcareous, siliceous rocks and hydrocarbon deposits. Therefore, they are beneficial as a source of food or chemical derivatives and the development of modern laboratory and cultivation technique. The classification of algae according the specific characteristics which define them. The types of important of algal species in microbiology, like bacillariophyta, euglenophyta, cyanobacteria, red algae and dinoflagellate.
The importance of diatoms must not be overlooked. These tiny organisms have been around for billions of years and play major roles in chemical and biological processes. Diatoms are estimated to be responsible for 20% to 25% of all the organic carbon fixation, are major sources of atmospheric oxygen, and are a major food source for aquatic microorganisms and insect larva (anonymous, 1999). Tiffany (1968) writes that marine diatoms are considered so important that they have been called "grass of the sea". This is because diatoms are major contributors to primary productivity in the oceans and create a beginning to the food chain.
Another important use of diatoms in the biological realm is in water quality testing. Research by Dixit et al (1999) show that diatoms can be used for present water quality but also used to determine former water quality and trends over the years. The sediments of lakes and rivers hold chemical and biological clues to the environment and water quality of the past and present. Diatoms are one of these clues. Because diatoms are ecologically diverse in almost every freshwater habitat, the dead and living diatoms can be found in the substrate. Diatoms in the first centimeter represent the current condition of the water, while the diatoms found in deeper sediment are representative of past water quality.
The high reproductive rates of diatoms make them respond quickly to environmental changes and many diatom species, as well, have specific tolerances for water quality. An important result of this research is that diatoms can be used to determine former water quality. This means that pre-colonial water quality can be estimated and used as a baseline to work from in determining anthropogenic effects on water quality. Diatoms help biologists see trends from past to present based on the sheer number, diversity and tolerance of diatoms in the sediment (Dixit et al, 1999).
Figure 1: Different structure of Diatoms
Euglena usually found in the pond and helps to give the nutrients to the surrounding organisms that live inside the ponds. Just few of them are growth in axenic culture and this culture are rich in nutrient which be used in preparation of algae during the experiment. The population of the algae also high in distribution and usually used as the experiment factor as it is produced in large of number which the population will never extinct (Hallick, R.B., L. Hong, 1993). The chloroplast is important to enable it to produce energy through photosynthesis. The energy is stored inside the cell and used during the locomotion and to engulf the small molecule during phagocytosis process.
Euglenophyta share both plants and animal characteristics as they are mixotrophs.. in sunlight they are autotrophs like plant but when the sunlight is unavaiable, they can become heterotrophic like animals. It is important components to enable freshwater plankton and food chains which support the transfer the energy in the energy cycle in the food chain. Beside that, they are also help to enables sensitive detection of DNA damage in eukaryotic cells introduced by genotoxic agents. In medicine, they act as assay organisms for vitamin B12.
Figure 2: Structure of Euglena
Cyanobacteria are also known as blue green algae. Cyanobacteria are a phylum of bacteria that obtain their energy through photosynthesis. Unicellular and filamentous cyanobacteria are almost invariably present in freshwater lakes frequently forming dense planktonic populations or water blooms in nutrient rich waters. In temperate lakes there is a characteristic seasonal succession of the bloom-forming species, due apparently to their differing responses to the physical chemical conditions created by thermal stratification (Soil & Water Conservation Society of Metro Halifax). Cyanobacteria are photosynthetic and can manufacture their own food (California department of public health).
Cyanobacteria account for 20-30% of Earth's photosynthetic productivity and convert solar energy into biomass-stored chemical energy at the rate of 450 TW. Cyanobacteria utilize the energy of sunlight to drive photosynthesis, a process where the energy of light is used to split water molecule into oxygen, proton and electron. Most of the high energy electrons derived from water are utilized by cyanobacteria cell for their own needs and fraction of these electron are donated to the external environment via electrogenic activity. This electrogenic activity is an important microbiological conduit of solar energy into biosphere.
Cyanobacteria are important organism for the growth of plant. Few groups of organisms can convert atmospheric nitrogen into an organic form such as nitrate or ammonia. Nitrogen needed for plant growth. Fertilizer works the way they do in part because it contain additional fixed nitrogen which plants can absorb through roots. Many plants, especially legumes have formed symbiotic relations with nitrifying bacteria, providing specialized tissues in their roots or stems to house the bacteria, in return for organic nitrogen. This has been used to great advantage in the cultivation of rice, where the floating fern is actively distributed among the rice paddies.
The ferns houses colonies of the cyanobacterium anabaena in its leaves, where it fixes nitrogen. The ferns then provide an inexpensive natural fertilizer and nitrogen source for the rice plants when they die at the end of the season. Cyanobacteria also form symbiotic relationships with many fungi, forming complex symbiotic "organisms" known as lichens (university of California museum of palaeontology).
Figure 3: Different stucture of Cyanobacteria
Red algae ( Rhodophyta).
Mostly, the red algae are cultivated in aquaculture operations for in use in human food or for extraction of gelling compounds. Dried porphyra (nori) obtained from aquaculture operations are important crops in Asia. The types of genera that had being consumed are Porphyra; Palmaria; Gracilaria; Gelidium; Eucheuma. The reasons for consumption include food value, flavour, colour, and texture. The structural carbohydrates of seaweeds are largely indigestible, but some soluble carbohydrates are metabolized. The protein content of many of the edible seaweed is 20-25% dry weight. Seaweed is an excellent source of vitamins (Kanazawa, 1963). The attractive flavour of Porphyra has been attributes to the presence of isofloridiosides and free amino acids ( McLachlan et al, 1972).
In addition, red algae contains polysaccharide substance (agar) and carrageenan as part of their cell wall. Agar solid substances media in microbiology is made from the red algae (Gelidium Amansii). Agar is a Malay word for the gelling substances extracted from Eucheuma, Which is ironically now known to be carrageenan. It is extracted from a number of species of Gelidium, and to a lesser extent from Gracilaria, Pterocladia, Acanthopeltis, and Ahnfeltia (Rhodophyceae). Like carrageenan, agar is basically composed of sulphated and pyruvated galactoses. The highest grades of agar produce stiff gels in 1-2% aqueous solution at normal temperature, but are liquefied when hot. They are principally used in the preparation of high-quality bacteriological and tissue culture media. Pure agarose is now used as a gel in electrophoretic and chromatographic studies (Pluzeck, 1981).
Carrageenan used as thickening agent in ice-cream and food. Carrageenans are polymers of sulphated or pyruvated galactose and 3,6-anhydrogalactose (McCandless, 1981). Carrageenan is used in the food industry as an emulsifier, particularly in dairy products; as a size in the textile and leather industries; and as an emulsifier in the pharmaceutical industry. Crude extract of many species of algae contain substances with antibiotic properties against bacteria, fungi, and viruses (Glombitza 1979). Antiviral compounds reported in red algae include polysaccharides containing D-glycosyl group, which are apparently active in the control of herpes viruses (Ehresmann el al, 1979). They act by blocking viral attachment points in the cell membrane.
Many seaweeds contain sterols and related ompounds, which are antagonistic to cholesterol in mammalian systems and may reduce elevated blood pressure associated with atherosclerosis (Chapman & Chapman, 1980). Carrageenan may be used to induce ulceration in the stomach and intestines of animal to test anti-inflammatory compounds (Di Rosa, 1972). It is reported not to cause ulcers in humans (Graso & Sharrat, 1973) and has been used in the treatment of peptic ulcers (MacPherson & Pfeiffer,1976). The abilities of carrageanans and alginates to form metal salts have suggested their use as non-toxic chelating agents in the treatment of heavy metal and radilnucleotide poisonings (Tanaka & Stara, 1979).
Gelidium amansii Porphyra
Figure 4: Types of Red Algae
Dinoflagellates are one of the most important components in plankton. Most dinoflagellates are primary producers in the aquatic food webs. Dinoflagellates are an integral part of the first link in the aquatic food chain: the initial transfer of light energy to chemical energy (photosynthesis). Almost all other organisms are dependent upon this energy transfer for their existence (Laura and Paolo 2006).
According to Dinoflagellates most dinoflagellates (90%) are marine plankton. They have adapted to the pelagic environment as free-floating in the water column, and to the benthic habitat . Benthic species can grow attached to stones (epilithic), on mud or sand (epipelic) on other algae or plants (epiphytic) or on animals (epizoic) (Laura and Paolo 2006). According to Dinoflagellates, some even serve as symbionts, known as zooxanthellae, providing organic carbon to their hosts: reef-building corals, sponges, clams, jellyfish, anemones and squid.
The most hazardous effect of dinoflagellates on their environment occurs in coastal waters. When the population becomes too large due to pollution with nutrients such as nitrogen and phosphate, dinoflagellates bloom will occur (Laura and Paolo 2006). 'Blooms' are cell population explosion, may cause discoloration of the water golden or red, and is called 'red tide' (due to accumulation of carotenoid pigments) (Laura and Paolo 2006). 'Red tides', have harmful effects on the sea life and their consumers.
Toxic blooms more intriguing and of public concern are the toxins that certain species produce. When these toxic species are in bloom conditions they can cause mass mortalities in a variety of marine organisms. The toxins can be quickly carried up the food chain which will indirectly pass onto humans via fish and shellfish consumption. It is sometimes results in gastrointestinal illness, permanent neurological damage, or even death (Laura and Paolo 2006).
Besides that, socioeconomic would be affected due to the closing of commercial fisheries and marine culture until the harmful algal bloom dissipates (Laura and Paolo 2006). Over the last several decades many areas of the world, including the United States, have experienced a growing trend in the incidence of toxic dinoflagellate blooms.
Prorocentrum mexicanum. Scrippsiella tifida Scrippsiella tifida
Figure 4: Few benthic species of dinoflagellates. (http://www.mnh.si.edu/highlight/sem/dinoflagellates.html)