Bacteria: biodegradation

Wanner BL (1994) Molecular genetics of carbon-phosphorus bond cleavage in bacteria. Biodegradation 5 175-184. 

Smith MR (1990) The biodegradation of aromatic hydrocarbons by bacteria. Biodegradation 1 191-206... 

Spormann, A. M., and F. Widdel, Metabolism of alkylbenzenes, alkanes, and other hydrocarbons in anaerobic bacteria , Biodegradation, 11, 85-105 (2000). 

Furukawa, K. (1994). Molecular genetics and evolutionary relationship of PCB-degrading bacteria. Biodegradation, 5, 289-300. 

In aquatic environments, the heavier and less vola-tile/soluble compounds in crude oil will adsorb to suspended solids and subsequently settle in the sediments. Some heavy fractions with high density may sink into the sediment. This happens after the initial removal of the smaller and more volatile chemicals by either dissolution or volatilization. This is followed by biodegradation of those crude oil constituents that can serve as a food source for bacteria. Biodegradation is a significant mechanism for removal of hydrocarbons released into the environment. However, this generally occurs on the order of months and years. It is not believed that there is significant bioaccumulation of petroleum hydrocarbons in aquatic organisms. 

Biogas is a mixture of combustible gases that is created during anaerobic fermentation caused by bacteria (biodegradation in the absence of oxygen) of biological substances containing hydrocarbons. 

In some cases bacteria may have biodegraded the oil, i.e. destroyed the light fraction. Many shallow accumulations have been altered by this process. An example would be the large heavy oil accumulations in Venezuela. 

RDX and HMX are rather more recalcitrant, especially under aerobic conditions, but there are promising indications that biodegradation can occur under some conditions, especially composting (67). Several strains of bacteria able to use RDX (and Triazine) as a sole source of nitrogen for growth have recentiy been isolated, and this is an area where rapid progress is being made. 

Polyesters are known to be produced by many bacteria as intracellular reserve materials for use as a food source during periods of environmental stress. They have received a great deal of attention since the 1970s because they are biodegradable, can be processed as plastic materials, are produced from renewable resources, and can be produced by many bacteria in a range of compositions. The thermoplastic polymers have properties that vary from soft elastomers to rigid brittie plastics in accordance with the stmcture of the pendent side-chain of the polyester. The general stmcture of this class of compounds is shown by (3), where R = CH3, n = >100, and m = 0-8. 

Use of dry chemical, alcohol foam, or carbon dioxide is recommended for cycloahphatic amine fire fighting. Water spray is recommended only to flush spills away to prevent exposures. In the aquatic environment, cyclohexylamine has a high (420 mg/L) toxicity threshold for bacteria (Pseudomonasputida) (68), and is considered biodegradable, that is, rnineralizable to CO2 and H2O, by acclimatized bacteria. 

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