Microbial degradation of petroleum hydrocarbons: Technology and mechanism

Abstract

The petrochemical industry has received considerable attention from many sectors in our society. Petroleum spill has been frequently reported due to the lack of appropriate protocols during exploration, refining, transportation, and storage. An in-depth knowledge of petroleum compounds before planning the best strategies of pollutant bioremediation. The petroleum composition is a mixture of different hydrocarbons. Typically, the most found molecules are alkanes, cycloalkanes, and hydrocarbon mono-aromatics, known as BTEX (benzene, toluene, ethylbenzene, and xylene isomers, ortho-, meta-, and para-xylene). Besides the environmental contamination, BTEX compounds deserve attention regarding their high toxicity and a potential threat to human health. Among the available technologies for remediating areas that were impacted by petroleum-derived fuels, microbial biodegradation has emerged as a very effective technique. These technologies can be used as a complementary action to other conventional treatment technologies. Many microorganisms can use BTEX as their only carbon source. An optimized BTEX biodegradation requires an abundant presence of electron acceptors, a high enzymatic expression and an enhanced microbial access to mono-aromatics hydrocarbons. The metabolic pathways related to hydrocarbon degradation will always depend on the microorganism and the growth conditions. Also, compounds will undergo biodegradation only if there are enzymes capable of catalyzing them. The microorganism P. putida has an outstanding metabolic versatility that allows its growth in many different carbon sources. There are many natural plasmids found in P. putida, including the TOL plasmid that provides the genes for degrading toxic mono-aromatic hydrocarbons. However, the strongest motivation behind biodegradation studies is to seek microorganisms with a wide range of metabolic pathways to degrade various pollutants with cost-effective procedures. Therefore, the purpose of this chapter is to expand the discussion about the BTEX bioremediation and microbial metabolism of hydrocarbons.