Biocatalytic lipoprotein bioamphiphile induced treatment of recalcitrant hydrocarbons in petroleum refinery oil sludge through transposon technology.

The present investigation employed transposon technology to enhance the degradation of recalcitrant petroleum hydrocarbons present in petroleum oil sludge by using biosurfactant hyper-producing strain Enterobacter xiangfangensis STP-3. Out of 2500 transposon induced mutants, mutants M257E.xiangfangensis and M916E.xiangfangensis hyper-produce biocatalytic lipoprotein biosurfactant by1.98 and 2.34 fold higher than wild-type strain. Transposon induced mutation also modified the amino acid composition which improved the hydrophobicity and thermal stability of the biosurfactants produced by mutants, compared to the wild-type biosurfactant. GC-MS and LC-MS-MS revealed that biosurfactants have pentameric lipid moiety and esterase as protein moiety. Increased biosurfactant hydrophobicity and yield by the mutants resulted in the enhanced bioavailability of petroleum hydrocarbons, thereby mutants M257E.xiangfangensis and M916E.xiangfangensis demonstrated better petroleum oil sludge degradation by 82% and 88% respectively, than wild-type (72%). Disrupted genes vgr G and pgm M in M257E.xiangfangensis and M916E.xiangfangensis respectively hyper-produce biosurfactant by competitive pathway inhibition and increased precursor availability mechanism. Hyper-production of biosurfactant was also validated by comparing the expression of biosynthetic genes ent E, ent F and est using qPCR. This is the first report on the application of transposon technology to hyper-produce biosurfactant for the effective bioremediation of hydrocarbon contaminated environments.

Biodegradation of petroleum refining industry oil sludge by microbial-assisted biocarrier matrix: process optimization using response surface methodology.

Safe disposal of petroleum oil sludge generated from crude oil storage tank bottom is a major challenge for petroleum refineries across the globe. The presence of long chain hydrocarbons in petroleum oil sludge are known to have effects on the environment through bioaccumulation or biosorption. The present study was focused to develop a modified bioremediation process using hydrocarbonoclastic microbial-assisted biocarrier matrix (MABC) mediated through biosurfactants and biocatalysts for the efficient treatment of petroleum industrial oily sludge. The development of hydrocarbonoclastic microbial-assisted biocarrier matrix was confirmed by scanning electron microscopy analysis. The biocatalysts such as lipase, laccase, esterase and biosurfactant produced by MABC system were found to be 40 U/mg, 18 U/mg, 36 U/mg and 220 mg/g of oil sludge respectively using one variable at a time approach. Further, the response surface methodology was used to determine the optimum treatment conditions (Time, pH, Mass of biocarrier matrix and Amount of oil sludge) for the enhanced removal of total petroleum hydrocarbons (TPH) present in the oil sludge and TPH was degraded by 88.78% at Hydraulic Retention Time of 7 days. The biodegradation of oil sludge was confirmed using Gas Chromatography-Mass Spectrometry analysis.