Metagenomic Sequencing of Formation Water Sample of Upper Assam Oil Fields and Its Possible Applications in Microbial Enhanced Oil Recovery

Abstract

Abstract In this study, we describe a metagenomic approach which is a Next Generation Sequencing Technique (NGS) for the identification of biosurfactant-producing microbes present in the formation water sample in the oil fields of Upper Assam. This study also intends to investigate the possible use of the Bacillus subtilis OQ957160 strain (sb23) in the brown fields of Upper Assam for improving recovery of crude oil. Biosurfactant-producing strains like Bacillus Subtilis, Bacillus licheniformis, Pseudomonas Putida, and Pseudomonas aeruginosa were isolated using 16s rRNA gene sequencing and were described and examined based on their capacity to degrade crude oil to produce biosurfactants. Bacillus subtilis OQ957160 strain (sb23) was selected for further study based on its biosurfactant production capability and better interfacial tension reduction (IFT) and surface tension (ST) properties. Through changes to the growing environment, such as carbon source, temperature, pH, and salinity, the dynamics of growth research of the identified strain sb23 was done. Lipopeptide (Surfactin) was identified as the produced biosurfactant. After 70 hours of incubation under ideal conditions, the maximum biosurfactant production of 6000 mg/L and the minimum interfacial tension & surface tension of 0.98 and 23.8 mN/m were attained. At the value of 475 mg/L the biosurfactant solution exhibited critical micelle concentrations (CMC). Additionally, the biosurfactant exhibits outstanding surface activity throughout a wide temperature range of 35-95°C and at salinities ranging from 0.0-16.0% (w/v) and pH 2.0 -10.0. Under reservoir conditions, the produced biosurfactant from strain (sb23) is used in microbial flooding tests to recover an additional 7.85% of heavy crude oil. As a result, the isolated strain sb23 has the potential to significantly improve oil recovery from depleted oil fields of Upper Assam.