Biosurfactants as microbial bioactive compounds in microbial enhanced oil recovery

Fossil fuels such as petroleum resources continue to be a significant fraction of the energy portfolio. Oil sludge or slops have become an unavoidable waste in the petroleum industries, and their improper disposal measures have led to environmental pollution. Various conventional and traditional practices for disposal and recovery are practiced, but the efficiency of MEOR has led to more promising and efficient ways to recover oil from oil reservoirs and waste sludges. Among the microbial bioactives, biosurfactants are the key players in the whole process. Although, MEOR using biosurfactants has been largely practiced for recovering oil from oil reservoirs, microbial metabolites are also proving to be effective in recovering oil from the waste oily sludges generated as a part of the petroleum production cycle. MEOR stands out as a economically sound alternative over other conventional methods that require large capital investment, heavy energy consumption and varying recovery efficiency. This review describes the scope of MEOR to be useful in reducing and reusing the waste oily sludge accumulation that when untreated causes environmental pollution, allowing sustainable use of natural resources. However, lack of reproducibility at field scale, large scale production of bioactive compounds are the major reasons leading to its incompatibility. The review aims to address the gaps and possible strategies to help speed up the efficiency by thoroughly focusing on the biosurfactant mediated MEOR process dynamics and use of various non-renewable substrates as measure of waste utilization for the production of metabolites. The molecular makeup of these significant molecules after extracting them from the contaminated niche will help discover microbial diversity. Furthermore, the limitations to this biosurfactant assisted MEOR can be solved by using genomic and high throughput approaches to execute an economical implementation at field scale level.