A real time integrated approach for the treatment of petroleum industry oily waste through ancillary carbon metabolism and biocatalytic cascade induction

Abstract

Recalcitrant hydrocarbons contamination by petroleum oil sludge (POS) disposal from the petroleum refining industry is a major environmental issue. Insufficient biomolecules (biosurfactant and degradative enzymes) production and passive metabolic transformation lead to more prolonged and incomplete bioremediation process. Herein, integration of ancillary carbon metabolism and biocatalytic cascade induction facilitated faster microbial growth, increased supply of precursors for macromolecule production and activated enzymatic degradation cascade. The agricultural by-product, rice husk found to be the suitable ancillary carbon source and elemental analysis of Carbon, Hydrogen and Nitrogen (CHN), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy analyses confirmed the microbial assimilation of the co-substrate. Divalent metal cations such as Cu2+, Fe2+ and Zn2+ were screened as essential enzyme activators, thereby induce the enzymatic degradation of POS. The integrative system exhibited the maximum aliphatic and aromatic hydrocarbons degradation of 96% and 92% during semi-pilot scale treatment (1 Kg of POS). Further, the functional annotation of the genome using Carbohydrate-active enzymes (CAZymes) provided specific insight into the genomic potential of E.xiangfangensis STP-3 in the concomitant metabolism of complex carbohydrates towards the enhanced enzymatic degradation of POS. These findings demonstrated that integrating ancillary metabolism and biomolecular machinery induction provides a sustainable POS clean-up strategy.