ABSTRACT
This chapter presents the composition of the petroleum-degrading microbial population of soil, the soil factors affecting the biodegradation process, the petroleum product chemical structure and its influence on the biodegradation process, and engineered bioremediation systems for treatment of petroleum products in soil. The heterogeneous or heterotrophic microorganisms found in soils include naturally occurring populations that possess the ability to degrade petroleum products. Spore-forming bacteria generally have a negligible role in biodegradation. Although Bacillus strains have been isolated from contaminated sods, this may be due to their persistence in soil and subsequent spore germination during enrichment and isolation procedures. Also, a number of actinomycetes have been shown to have hydrocarbon-degrading abilities; however, the microorganisms do not seem to compete successfully in contaminated soils. Populations of Arthrobacter and coryneforms such as Corynebacterium, Brevibacterium, Mycobacterium, and Nocardia showed strong positive responses to oil contamination.
