Biodegradable and Non-Biodegradable Substances

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BIODEGRADABLE SUBSTANCES
Biodegradable matter is generally organic materials such as plant and animal matter and other substances originating from living organisms, or artificial materials that are similar enough to plant and animal matter to be put to use by microorganisms. Some microorganisms have a naturally occurring, microbial catabolic diversity to degrade, transform or accumulate a huge range of compounds including hydrocarbons (e.g. oil), polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), pharmaceutical substances, radionuclides and metals. Major methodological breakthroughs in microbial biodegradation have enabled detailed genomic, metagenomic, proteomic, bio-informatic and other high-throughput analyses of environmentally relevant microorganisms providing unprecedented insights into key biodegradative pathways and the ability of microorganisms to adapt to changing environmental conditions.[1] Products that contain biodegradable matter and non-biodegradable matter are often marketed as biodegradable. Research efforts in this field are two-fold: to identify and/or develop transgenic biological agents that digest specific existing compounds in polluted soils and water, and to develop new biodegradable compounds to replace hazardous chemicals in industrial activity. Research is, therefore, aimed at bioremediation, which could identify biological agents that rapidly degrade existing pollutants in the environment, such as heavy metals and toxic chemicals in soil and water, explosive residues, or spilled petroleum. Crude oil however, is naturally biodegradable, and species of hydrocarbon-degrading bacteria are responsible for an important reduction of petroleum levels in reservoirs, especially at temperatures below 176° F (80° C). The selection, culture, and even genetic manipulation of some of these species may lead to a bioremediation technology that could rapidly degrade oil accidentally spilled in water. Another field for biodegradable substances usage is the pharmaceutical industry, where biomedical research focuses on non-toxic polymers with physicochemical thermo-sensitivity as a matrix for drug delivering. One research group at the University of Utah at Salt Lake City in 1997, for instance, synthesized an injectable polymer that forms a non-toxic biodegradable hydro gel that acts as a sustained-release matrix for drugs. Transgenic plants expressing microbial genes whose products are degradative enzymes may constitute a potential solution in the removal of explosive residues from water and soils. A group of University of Cambridge and University of Edinburgh scientists in the United Kingdom developed transgenic tobacco plants that express an enzyme (pentaerythritol tetranitrate reductase) that degrades nitrate ester and nitro aromatic explosive residues in contaminated soils. Another environmental problem is the huge amounts of highly stable and non-biodegradable hydrocarbon compounds that are discarded in landfills, and are known as polyacrylates. Polyacrylates are utilized as absorbent gels in disposable diapers, and feminine hygiene absorbents, as well as added to detergents as dispersants, and are discharged through sewage into underwater sheets, rivers, and lakes. A biodegradable substitute, however, known as polyaspartate, already exists, and is presently utilized in farming and oil drilling. Polyaspartate polymers are degradable by bacteria because the molecular backbone is constituted by chains of amino acids; whereas polyacrylates have backbones made of hydrocarbon compounds. The main challenge in the adoption of biodegradable substances as a replacement for existing hazardous chemicals and technologies is cost effectiveness. Only large-scale production of environmental friendly compounds can decrease costs. Public education and consumer awareness may be a crucial factor in the progress and consolidation of "green" technologies in the near future.

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