Abstract
Biosurfactant plays an important role in bioremediation of crude oil contamination and microbial enhanced oil recovery (MEOR). In the present study, a salt-tolerant, biosurfactant-producing bacterium, designated A-8, was isolated from wastewater contaminated with petroleum collected from the Changqing reservoir in China. A phylogenetic analysis based on the 16S rRNA sequence suggests that strain A-8 belongs to the genus Achromobacter. The optimal growth conditions for strain A-8 in mineral salt (MS) medium were 30°C, pH 7, and 10 g/L NaCl, while the optimal conditions for biosurfactant production in a fermentation medium were 40–45°C, pH 7, and more than 70 g/L NaCl. Better biosurfactant production was obtained from strain A-8 when edible oil and liquid paraffin were used as carbon sources and when (NH4)2SO4 was used as an inorganic nitrogen source compared with other tested carbon and nitrogen sources. The biodegradation of petroleum in MS medium in different optimized conditions reached 56.23–73.87% for 20 days. The biodegradation of petroleum, together with the production of organic acid and biosurfactant, decreased the viscosity of petroleum by about 45%. The decrease in petroleum viscosity and the biodegradation of petroleum suggest the potential use of strain A-8 for MEOR and bioremediation of petroleum-contaminated environments.
Highlights
As a non-renewable resource, petroleum will gradually decrease with its continuous exploration
The microbial metabolites, such as biosurfactant and organic acid are reported as key players in Microbial enhanced oil recovery (MEOR) (Voordouw, 2011)
Most of the bacteria strains were belonged to genus Bacillus, especially species B. cereus, which already had been widely reported involved in crude oil degradation (Banerjee and Ghoshal, 2010; Janaki et al, 2016)
Summary
As a non-renewable resource, petroleum will gradually decrease with its continuous exploration. Three methods are usually used for petroleum exploration in oil reservoir fields: primary (5–10%), secondary (30–40%), and tertiary, which is called enhanced oil recovery (EOR) (Datta et al, 2018; Geetha et al, 2018). EOR includes physical, chemical, and biological methods (Sen, 2008; Li et al, 2011; Mozhdehei et al, 2019). Physical and chemical methods mainly aim to decrease the viscosity of the petroleum to enhance petroleum recovery. These methods have their own Petroleum Degrading Bacteria and MEOR limitations, such as high cost, environmental unfriendliness, and complicated operation. The isolation and identification of crudeoil-degrading and biosurfactant-producing microorganisms are important parts of MEOR
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