The following points highlight the eight main areas of environmental biotechnology. The areas are: 1. Waste Treatment 2. Biodegradation 3. Microorganisms in Pollution Control 4. Biomass Energy Production 5. Biosensors and Bio-Monitoring 6. Bioremediation 7. Restoration of Degraded Lands 8. Biodiversity Conservation.
Area # 1. Waste Treatment:
The overall production of methane from organic wastes is a complex fermentation involving a number of groups of microorganisms (Methanogens, member of Archaebacteria). They utilize the anaerobic environment and organically enriched sediments.
The aerobic waste treatment requires a large population of actively metabolizing microorganisms such as Pseudomonas, Alcaligenes, Achromobacter and Brevibacterium, able to degrade both colloidal and soluble organics with high rate of conversion of CO2 and water.
Due to anaerobic decomposition of organic waste material, the most important component produced is methane, which can be easily collected and used as biogas fuel. Other than methane, some other products are produced due to the activity of facultative anaerobes.
The nitrogenous waste materials are treated both aerobically and anaerobically alternatively. The degradation of nitrogenous compounds gives ammonia, which is then converted to nitrate by nitrifying bacteria. Then by the action of denitrifying bacteria in anaerobic environment releases N2 gas in the atmosphere.
Area # 2. Biodegradation:
It is the process by which materials such as oil spill, herbicides, pesticides, etc. are degraded by the action of microbial system. Organic compounds which are naturally occurring (biogenic) are biodegradable while man-made (xenobiotic) compounds may be biodegradable, persistent or recalcitrant.
Genes coding for sortie enzymes essential for the biodegradation of a number of organic compounds are plasmid borne and organisms have been constructed to degrade difficult waste. A strain of Pseudomonas putida is constructed to contain plasmids coding for the breakdown of octane, xylene, metaxylene and camphor. This organism is claimed to be useful for cleansing of oil spills.
Area # 3. Microorganisms in Pollution Control:
Microbial strains can be isolated in order to control various forms of chemical pollution such as biocides, detergents, plastic materials and hydrocarbons. The bacteria belonging to the genus Pseudomonas have oxidoreduction or hydroxylation enzymes capable of degrading a large number of hydrocarbon molecules or aromatic compounds that are often highly toxic.
Genetic recombination techniques should make it possible to achieve such a result that a single microbial strain will be capable of decomposing and assimilating numerous compounds, most often non-biodegradable (xenobiotic), produced by the chemical industry.
Area # 4. Biomass Energy Production:
Environmental biotechnology also deals with various sources of energy. Biomass is the living matter or its residues, a perpetual or renewable source of energy. Ethanol is formed from various sources, such as cassava, cereals, potato, sugarcane, pineapple, sugarbeet, etc. It is a solvent and also a substrate for the synthesis of many other components and dyes.
Biogas formation and methanogenesis are although ancient forms, today they are in great demand. Methane fermentation is widely practiced and is one of the easily available sources of energy. Agricultural wastes and farmyard wastes are efficiently used for this purpose. Production of biogas in rural areas has been a priority in the energy policy of India.
Area # 5. Biosensors and Bio-Monitoring:
Biosensors represent biophysical devices’ which can detect and measure the quantity of specific substance in a variety of environments and thus may be used in environmental monitoring.
Area # 6. Bioremediation:
Microbes and higher plants which can destroy or reduce the concentration of hazardous wastes from a contaminated site can be subjected to modify variously through genetic engineering to become efficient and more suitable for bioremediation. Genetically engineered Pseudomonas have been used for degradation of PAH (Polyaromatic hydrocarbons) in soil, treating oil spills.
De-toxication of soil contaminated with heavy metals can be done by growing certain plant species called phytoremediation through phyto-extraction, rhizofiltratioin, phyto-degradation or Phyto-stabilization. Transgenic Arabidopsis thaliana plants have been produced for detoxification of soils contaminated with mercury, aluminium, arsenic and transgenic tobacco developed for enhanced TNT (explosive) detoxifying ability.
Area # 7. Restoration of Degraded Lands:
With the advent of biotechnology, unprecedented opportunities for recovery of degraded lands have become available through the manipulation of biological systems. Reforestation though micropropagation, development of stress tolerant plants, use of mycorrhizae, use of microbes for improving soil fertility are some of the measures in this regard.
Area # 8. Biodiversity Conservation:
To avoid the extinction of endangered or threatened plant species, conservation may be carried out by establishing Gene Banks/Genetic Resource Centres using biotechnological devices like plant tissue culture.
Cryopreservation technology is the most popular and effective method for long term storage of plant cell and tissues which involves storage at a very low temperature. The method includes the raising of sterile tissue cultures, addition of cryoprotectant, freezing, storage.
The eventual regeneration from the cryopreserved tissue needs thawing, determination of viability and again growth and regeneration ability. The tissues are kept either in Dry ice (-79°C) or Liquid N2 (-196°C); storage at this temperature halts the metabolic process and biological deterioration. Many of the tropical plants’ tissues, embryos have been successfully cryopreserved.