Microbial degradation of hydrocarbons in the environment: An overview

Biodegradation of hydrocarbons is a cost-effective technique that is based on highly dispersed microbes in soil and water capable of biodegrading hydrocarbons. Degradation is an effective method for remediation of petro-hydrocarbons and causes changes in nature and concentration of petro-compounds. Biodegradation is classified as the most important tool for eliminating the toxicity and for removing the hydrocarbons in the different environments such as soil, water, and soil sediment that are polluted by hydrocarbons. The microorganisms employed in degradation process must be aboriginal in polluted sites. Investigators have recently discovered a large number of microbial groups from the sediment, water, and soil that have been polluted by crude petroleum oil. These microorganisms were able to transform hydrocarbons to energy and biomass as well as biological waste by-products. A variety of microorganisms have such capability of cleaning up and remediating locations that polluted by hydrocarbons. The microorganisms that biodegrade hydrocarbons are widely dispersed within surface water, sediments, and soil habitats. The importance of these microorganisms in biodegrading hydrocarbons and their other natural organic residues in aquatic ecosystems, soil, and sediment has long been recognized. Transformation of organic contaminants by these microbes naturally occurs because these organisms are able to use organic contaminants for their energy and carbon requirement as well as for their development and propagation. The capability of particular microbes to biodegrade the petro-hydrocarbons appears to be an acclimatization and is managed by several ecological factors. Primarily, the presence of hydrocarbons may also affect the microorganism community owing to its different chemical nature. Petro-hydrocarbon biodegradation, by employing several microbial groups, is based largely on the structure of these communities as well as their adaptation in hydrocarbon contaminants. Bacterial and fungal strains are the main organisms for such crude oil biodegradation. Bacteria play a predominant role within the marine ecosystem, while fungi are more effective within both freshwater and earthen environment. The adaptive microorganism groups, which were formerly exposed to the petroleum hydrocarbon pollution, display much great degradation potential that exceeds other groups which has not exposed to such pollution. The microbial adaptation mechanism involves physical adjustment as well as some genetic changes, which leads to mutations. The mutation genes associated with the plasmid DNA could cause frequency increase in the plasmid-bearing microbes. In addition, seeding petroleum-polluted water and soil using microorganisms that feed on hydrocarbons exhibits significant success. Biodegradation of complex hydrocarbon pollutants needs a particular combination of more than one type of microbial group. This is mainly due to the fact that a single microorganism can only metabolize a limited amount of hydrocarbon substrates. Thus, the mixed cultivation (consortium) and the extensive enzymatic abilities of the microbes are strongly desired to enhance hydrocarbon degradation ratio.