from Anna-Irini Koukkou and Elpiniki Vandera writing in Microbial Bioremediation of Non-metals: Current Research:
Hydrocarbons are the major representatives of non-metal pollutants found in many contaminated soils by natural or industrial and social activities. Their removal from polluted environmental niches depends to a great extent on microbial degradation, which can also be applied on several technological applications. The extended microbial diversity in soil has served as a rich source for the isolation of efficient PAH-degrading strains. Bacterial isolates with the ability to use PAHs as an alternative source of carbon and energy facilitate their mineralisation to harmless products. Culture-based approaches have resulted in the isolation of a range of soil hydrocarbon-degrading bacteria, which primarily are members of different subdivisions of Proteobacteria as well as of the high G+C Gram-positive bacteria. Generally, in polluted-soils Gram-negative bacteria such as Pseudomonas, Burkholderia and Sphingomonas seem to degrade preferentially lower molecular weight PAHs such as naphthalene and phenanthrene, while Gram-positive isolates are more specialized in the degradation of high molecular weight PAHs such as pyrene.
Further reading: Microbial Bioremediation of Non-metals: Current Research