Biosurfactant and biopolymer producing microorganisms from West Kazakhstan oilfield

Abstract

Microbiological enhanced oil recovery (MEOR) uses indigenous or exogenous microorganisms and nutrients to enhance oil production through synthesis of metabolites reducing oil viscosity and surface tension. In order to find bacteria suitable for MEOR, we studied 26 isolates from wells in the Akingen oilfield in West Kazakhstan. Six of them were selected for further analysis based on their ability to reduce surface tension to less than 40 mN/m, with the A9 isolate exhibiting tension reduction values of 32.76 ± 0.3 mN/m. Based on the morphological features, biochemical activities, and the 16S rRNA gene, the isolates were classified to the Bacillus subtilis group. In the phylogenetic analysis the isolates grouped into two main clusters. Genes encoding the surfactin synthetase subunits were found in A2, A8, A9, A12, PW2, only the PW2 strain had lchAA encoding lichenysin, while sacB encoding levan was noted in A2, A8, A9, and A12. The expression of srfAB, srfAC, and sacB tested with qPCR varied among strains. Nevertheless, whereas temperature moderately affects the expression level, with the highest level recorded at 40 °C, salinity significantly impacts the expression of the genes encoding biosurfactants. B. subtilis strains isolated in the study, especially A9, are promising for microbial-enhanced oil recovery.

Oil dispersion characterization of microorganisms producing biosurfactants

“…To determine microbial emulsification and oil displacement, heavy, crude oil from the Ariskum field was used. It is known that the formation of various target metabolites in microorganisms is related to specific genes, such as the synthesis of biosurfactants linked to microbial oil emulsification and the ability of bacteria to reduce interfacial tension is governed by the presence of genes lchAA, rhlA, srfA [12,19].…”

“…A non-microbial version was used as a control. Earlier, the genes responsible for the production of low-molecular-weight biosurfactants, which contribute to oil displacement and emulsification, were identified in these bacteria [12,13]. It is known that in the bacteria of the Pseudomonas and Bacillus genera, the genes rhlA, srfA, lchAA are responsible for the ability to displace oil, based on the synthesis of low-molecular-weight biosurfactants that effectively reduce surface and interfacial tension [21,22].…”

“…subtilis A12, Bacillus subtilis A9 from the collection of the Department of Biotechnology, Al-Farabi Kazakh National University. Previously, the authors have determined the presence of lchAA, rhlA, srfA genes responsible for the formation of biosurfactants associated with microbial oil emulsification and the ability of bacteria to reduce interfacial tension [12,13].…”

Microbial communities in petroleum refinery effluents and their complex functions

“…The exceptional surface activity of biosurfactants is well-documented, encompassing the ability to decrease surface and interfacial tension among various phases, such as liquid–air, liquid–liquid, and liquid–solid. Adsorption of biosurfactants at various phases enables the reduction of surface and interfacial tension, resulting in enhanced contact and mixing of dissimilar phases ( Shaimerdenova et al, 2024 ).…”