Halophiles in bioremediation of petroleum contaminants: challenges and prospects

Abstract Crude oil formation and production is intrinsically accompanied by extreme conditions including high salinity. The presence of saline formation water (brine), injection of seawater for enhanced oil recovery, and application of saline drilling muds are all examples which highlight the presence of high salt concentration in different parts of the oil industry. Halophilic microorganisms, a group of extremophiles dependent on the presence of salt for their growth, have been associated with crude oil since its formation. Recent advances in molecular techniques, like next-generation sequencing, have led to new insights into the subsurface microbiology. This chapter focuses on the presence of halophilic prokaryotes in oil reservoirs and their application in different stages of the petroleum industry such as for microbial-enhanced oil recovery, biological gas sweetening, and microbial-induced corrosion. Furthermore, the efficacy of halophiles in the bioremediation of various pollutants of petroleum industry released to saline ecosystems will be discussed.