Enhancement of Biosurfactant Production by Bacteria Isolated from Crude Oil through Adaptation Laboratory Evolution

Abstract

Biosurfactant is widely used in the petroleum industry since it can increase oil recovery. However, its productivity remains economically inefficient. Through the adaptation laboratory evolution (ALE), it is possible to improve the biosurfactant productivity of targeted bacteria. This study aimed to enhance biosurfactant production by bacteria through the ALE and characterize the biosurfactant properties. Cetyltrimethylammonium bromide (CTAB) was used as a mutagen at concentrations ranging from 3.9 ppm to 10 ppm. The biosurfactant characterizations conducted were: 1) interfacial surface tension (IFT), 2) emulsification index (E₂₄), and 3) biosurfactant structure. The biosurfactant activity from the CTAB-resistant strain (KG7') had 3.3 folds higher IFT reduction with increasing production yield (Y_p/x) up to 2.6 folds (18.75 ± 1.53 mg/10⁸ CFU) compared to wildtype (WT) (7.07 ± 0.89 mg/10⁸ CFU). The KG7’, which was resistant at 4.5 ppm CTAB (KG7’b), was stable after the extension of the ALE process and had higher biosurfactant activity than WT. The structural properties of WT and mutant biosurfactants were both belong to the lipopeptide class. As a result, the ALE offers a potential tool for enhancing bacterial biosurfactant production.

Keywords:

• ALE
• biosurfactant
• CTAB
• emulsification
• lipopeptide

Acknowledgments

The authors would like to acknowledge Oil and Gas Recovery for Indonesia (OGRINDO) ITB for providing crude oil samples.

Author contributions

DIA, K, NR, and GGSN design the experiments; GGSN and NR conducted the research; DIA, K, NR, and GGSN analyze the data; K and NR drafted the paper; DIA, IT, VSHS finalized the drafted paper. All authors read, commented, and approved the final version of the manuscript.

Disclosure statement

All the authors declare there is no conflict of interest regarding this article.

Additional information

Funding

This study was funded by Institut Teknologi Bandung, under the scheme of ITB Research and Innovation Program (PPMI-ITB) under Grant [2.A/IT1.Cll/SK-PL/2021].