Biocatalytic lipoprotein bioamphiphile induced treatment of recalcitrant hydrocarbons in petroleum refinery oil sludge through transposon technology
2022
Muneeswari, R. | Iyappan, S. | Swathi, K.V. | Vinu, R. | Ramani, K. | Sekaran, G.
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.
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