Role of biosurfactants on microbial degradation of oil-contaminated soils

Hydrocarbon contamination of soil is one of the major environmental problems today due to activities related to the petrochemical industry. Mechanical and chemical remediation and restoration to remove hydrocarbons from contaminated sites have limited effectiveness and costly. Bioremediation is the promising technology for the treatment of these contaminated sites since it is cost-effective and will lead to complete mineralization. Fungi and bacteria have been considered as highly effective in oil degradation. Several bacteria are even known to feed exclusively on hydrocarbons; Arthrobacter, Burkholderia, Mycobacterium, Pseudomonas, Sphingomonas, and Rhodococcus. Fungal genera, namely, Amorphoteca, Neosartorya, Talaromyces, and Graphium are proved to be the potential organisms for hydrocarbon degradation. Although laboratory experiments have indicated that the bacteria can ubiquitously degrade oil constituents, to date there is little convincing evidence that bioaugmentation (addition of more bacteria) significantly enhances the extent of oil biodegradation in soil. The potential benefits of using genetically modified bacteria represent a research frontier with significant results. However, many concerns are often raising due to the effectiveness of indigenous species, limited understanding of various phytoremediation mechanisms, including the regulation of enzyme systems that degrade pollutants. Thus, this chapter presents an updated overview of petroleum hydrocarbon degradation by microorganisms focusing biosurfactants and their mechanisms.