Purification and characterization of antibacterial surfactin isoforms produced by Bacillus velezensis SK

Sagar S Barale; Savaliram G Ghane; Kailas D Sonawane

doi:10.1186/s13568-022-01348-3

Purification and characterization of antibacterial surfactin isoforms produced by Bacillus velezensis SK

AMB Express. 2022 Jan 27;12(1):7. doi: 10.1186/s13568-022-01348-3.

Authors

Sagar S Barale¹, Savaliram G Ghane², Kailas D Sonawane^{3

4}

Affiliations

¹ Department of Microbiology, Shivaji University, Kolhapur, 416004, Maharashtra, India.
² Department of Botany, Shivaji University, Kolhapur, 416004, Maharashtra, India.
³ Department of Microbiology, Shivaji University, Kolhapur, 416004, Maharashtra, India. kds_biochem@unishivaji.ac.in.
⁴ Structural Bioinformatics Unit, Department of Biochemistry, Shivaji University, Kolhapur, 416004, Maharashtra, India. kds_biochem@unishivaji.ac.in.

Abstract

Bacillus velezensis SK having broad-spectrum antimicrobial activity has been isolated from soil. The efficient extraction of antimicrobial compounds produced in various mediums has been done using Diaion HP-20 resin. Further, characterization of an antimicrobial compound by TLC, FTIR, in-situ bioautography analysis revealed the presence of cyclic lipopeptides, which is then purified by the combination of silica gel, size exclusion, dual gradient, and RP-HPLC chromatography techniques. Growth kinetic studies showed that Bacillus velezensis SK produces a mixture of lipopeptides (1.33 gL^-1). The lipopeptide exhibits good pH (2-10) and temperature stability up to 80 °C. LC-ESI-MS analysis of partially purified lipopeptide identified variant of surfactin, further analysis of purified chromatographic fractions revealed the occurrence of most abundant C₁₅-surfactin homologues (m/z 1036.72 Da). The isolated surfactin exhibits good antimicrobial activity (1600 AU/ml) against drug-resistant food-born B. cereus and human pathogen Staphylococcus aureus. Hence, identified strain B. velezensis SK and its potent antibacterial surfactin lipopeptide could be used in various food and biomedical applications.

Keywords: Antibiotic-resistance; Antimicrobial peptides; B. velezensis SK; LC–ESI–MS; Lipopeptide; RP-HPLC.