8. BIODEGRADATION
Biodegradation is nature's way of recycling wastes or breaking down the organic contaminants by microbial organisms into smaller compounds. "Degradation" means decay, and the "bio-" prefix means that the decay is carried out by a huge assortment of bacteria, fungi, insects, worms, and other organisms that eat dead material and recycle it into new forms. The microbial organisms transform the contaminants through metabolic or enzymatic processes. Biodegradation processes vary greatly, but in most cases the final product of the degradation is carbon dioxide or methane. Biodegradation is a key processes in the natural attenuation of contaminants at hazardous waste sites. Organic material can be degraded aerobically, with oxygen, or anaerobically, without oxygen. A term related to biodegradation is biomineralisation, in which organic matter is converted into minerals.

Biodegradable waste in landfill degrades in the absence of oxygen through the process of anaerobic digestion. The byproducts of this anaerobic biodegradation are biogas and lignin and cellulose fibres which cannot be broken down by anaerobes (anaerobic microbes).  Engineered landfills are designed with liners to prevent toxic leachate seeping into the surrounding soil and groundwater. Paper and other materials that normally degrade in a few years degrade more slowly over longer periods of time. Biogas contains methane which has approximately 21 times the global warming potential of carbon dioxide. In modern landfills this biogas can be collected and used for power generation.


Where does Biodegradation contribute to environmental biotechnology:

As it is stated that, biodegradation is the nature’s way of waste recycling, i.e. it acts as a natural cleaning mechanism of biodegradable wastes materials like market waste, domestic wastes etc. the environmental biotechnology has explored wide scope of the same in waste management. By harnessing these natural forces of biodegradation, people can reduce wastes and clean up some types of environmental contaminants. Through composting, we accelerate natural biodegradation and convert organic wastes to a valuable resource. Wastewater treatment also accelerates natural forces of biodegradation. In this case the purpose is to break down organic matter so that it will not cause pollution problems when the water is released into the environment. Through bioremediation, microorganisms are used to clean up oil spills and other types of organic pollution. Composting and bioremediation provide many possibilities for student research.

Bacteria have evolved over millions of years to be able to get energy and nutrients from chemicals, in a process called biodegradation. Bacteria grow by breaking down chemicals into smaller compounds, nutrients and water. With the nutrients and energy produced, more bacteria are formed. Since many ingredients are made up mostly of carbon atoms, bacteria may be able to convert that ingredient into CO2, water and nutrients. Certain enzymes produced by microbes attack hydrocarbons molecules, causing degradation. For example, the degradation of oil relies on having sufficient microbes to degrade the oil through the microbes’ metabolic pathways (series of steps by which degradation occurs). Fortunately, nature has evolved many microbes to do this job.

Oil Degrading Bacteria and Fungi
Bacteria
Fungi
Achromobbacter
Allescheria
Acinetobacter
Aspergillus
Actinomyces
Aureobasidium
Aeromonas
Botrytis
Alcaligenes
Candida
Arthrobacter
Cephaiosporium
Bacillus
Cladosporium
Beneckea
Cunninghamella
Brevebacterium
Debaromyces
Coryneforms
Fusarium
Erwinia
Gonytrichum
Flavobacterium
Hansenula
Klebsiella
Helminthosporium
Lactobacillus
Mucor
Leucothrix
Oidiodendrum
Moraxella
Paecylomyces
Nocardia
Phialophora
Peptococcus
Penicillium
Pseudomonas
Rhodosporidium
Sarcina
Rhodotorula
Spherotilus
Saccharomyces
Spirillum
Saccharomycopisis
Streptomyces
Scopulariopsis
Vibrio
Sporobolomyces
Xanthomyces
Torulopsis

Trichoderma

Trichosporon


Organic Compounds Degradative Bacteria
Organic compounds
Bacterial strain
Aniline
Frateuria sp. ANA-18

Nocardia sp.

Pseudomonas sp.

Pseudomonas multivorans AN1

Rhodococcus sp. AN-117

Rhodococcus sp. SB3
Anthracene
Beijerinckia sp. B836

Cunninghamella elegans

Pseudomonas sp.

Pseudomonas putida 199
Benzene
Achrommobacter sp.

Pseudomonas sp

Pseudomonas aeruginosa

Pseudomonas putida
Benzoic acid
Alcaligenes eutophus

Aspergillus niger

Azotobacter sp.

Bacillus sp.

Pseudomonas sp.

Pseudomonas acidovorans

Pseudomonas testosteroni

Pseudomonas sp. Strain H1

Pseudomonas PN-1

Pseudomonas sp. WR912

Rhodopseudomonas palustris

Streptomyces sp. by consortia of bacteria
2-Chlorobenzoic acid
Aspergillus niger
3-Chlorobenzoic acid
Acinetobacter calcoaceticus Bs5 (grown on succinic acid and pyruvic acid)

Alcaligenes eutrophus B9

Arthrobacter sp. (grown on benzoic acid)

Aspergillus niger

Azotobacter sp. (grown on benzoic acid)

Bacillus sp.  (grown on benzoic acid)

Pseudomonas aeruginosa B23

Pseudomonas putida (WITH PLASMID P AC25)

Pseudomonas sp. B13

Pseudomonas sp. H1

Pseudomonas sp. WR912 by consortia of bacteria
4-Chlorobenzoic acid
Arthrobacter sp.

Arthrobacter globiformis

Azotobacter sp.   (grown on benzoic acid)

Pseudomonas sp. CBS3

Pseudomonas sp.WR 912
4-Chloro-3,5-dinitrobenzoic acid
Chlamydomonas sp.
2,5-Dichlorobenzoic acid
By consortia of bacteria
3,4-Dichlorobenzoic acid
By consortia of bacteria
3,5-Dichlorobenzoic acid
Pseudomonas sp. WR912 by consortia of bacteria
2,3,6-Trichlorobenzoic acid
Brevibacterium sp. (grown on benzoic acid)
Biphenyl
Beijerinckia sp.

Beijerinckia sp. B836

Beijerinckia sp. 199

Cunninghamella elegans

Pseudomonas putida by consortia of bacteria
Catechol
Pyrocatechase 1
4-Chlorocatechol
Achromobacter sp.
3,5-Dichlorocatechol
Achromobacter sp.
Chlobenzene
Pseudomonas putida (grown on toluene)

Unidentified bacterium, strain WR1306
Chlorocatechol
Pyrocatechases
3,5-Dichlorocatechol
Achromobacter sp. (grown on benzoic acid)
Chlorophenol
Arthrobacter sp.
2-Chlorophenol
Alcaligenes eutrophuis

Nocardia sp. (grown on phenol)

Pseudomonas sp. B13
3-Chlorophenol
Nocardia sp. (grown on phenol)

Pseudomonas sp.B13

Rhodotorula glutinis
4-Chlorophenol
Alcaligenes eutrophuis

Arthrobacter sp.

Nocardia sp. (grown on phenol)

Pseudomonas sp. B13

Pseudomonas putida
2,4,6-Trichlorophenol
Arthrobacter sp.
2,3,4,6-Tetrachlorophenol
Aspergillus sp.

Paecilomyces sp.

Penicillium sp.

Scopulariopsis sp.
Chlorotouene
Pseudomonas putida  (grown on toluene)
Gentisic acid
Trichosporon cutaneum
Guaiacols (o-methoxyphenol)
Arthrobacter sp.
3,4,5-Trichloroguaiacol
Arthrobacter sp.1395
Homoprotocatechuic acid
Trichosporon cutaneum
Napthalene
Cunninghamella elegans

Oscillatoria sp.

Psedomonads
Pentachlorophenol (PCP)
Arthrobacter sp.

Coniophora pueana

Mycobacterium sp.

Pseudomonas sp.

Saprophytic soil corynebacterium

KC3 isolate

Mutant ER-47

Mutant ER-7

Trichoderma viride
Phenanthrene
Aeromonas sp.

Flurescent and nonfluorescent pseudomonad groups

Vibrios
Protocatechuic acid
Neurospora crassa

Trichosporon cutaneum
Sodium pentachlorophenate (Na-PCP)
Trichoderma SP.

Trichoderma virgatum
Tertachlorohydroquinone
KC3
Tolune
Accromobacter sp

Pseudomonas sp.

Pseudomonas aeruginosa

Pseudomonas putida
4-Amino-3,5-dichlorobenzoic acid
By consortia of bacteria
2,4,5-Trichlorophenoxyacetic acid
Pseudomonas cepacia AC1100


Source: Complied from Rochkind, M.L. etal., 1986, Microbial Decomposition of Chlorinated Aromatic Compounds, EPA/600-86/090, CHAP.6-10, PP. 45-98