Antimicrobial potential of secondary metabolites and DNA gyrase B blocking molecules produced by a halophilic bacterium Virgibacillus salarius (MML1918)

Abstract

Abstract Aim The present study aims to determine the antimicrobial potential of Virgibacillus salairus (MML1918) against human pathogens and its in-vitro and in-silico properties. Methods and results In this present study, totally 63 halophilic bacterial cultures were obtained and cultivated in nutrient broth medium containing 8% NaCl and the metabolites, were extracted using ethyl acetate and screened for their antimicrobial property by cell viability assay against 12 pathogenic bacteria and fungi, among 63 halophilic bacteria the Vir. salaries (MML1918) found to be the best producer for secondary metabolites production against clinical pathogens. The optimization of growth for important physiochemical parameters was characterized and applied for different production media and based on its highest activity as 17.5 ± .07 mm zone of inhibition (ZOI) for Bacillus cereus followed by 17.5 ± 00 mm ZOI for Staphylococcus aureus, the production medium ATCC1097 was chosen for mass production. The mass production of secondary metabolites from Vir. salaries MML1918 was carried out in a fermenter under controlled conditions and crude metabolites was extracted and condensed. The antimicrobial activity of crude metabolites showed B. cereus (19.3 ± 0.5 mm ZOI), Staph. aureus, and Candida albicans (18.3 ± 0.5 mm ZOI) as the highest ZOI in production media for halophilic bacteria ATCC1097. Further, the gas chromatography–mass spectrometry analysis showed 24 compounds present in crude metabolites. Among the 24 compounds, four molecules were found to be important based on molecule percentage in crude and structural similarity. The molecular docking studies show that the selected four molecules effectively bind with the active region DNA gyrase B. Conclusion Virgibacillus salarius (MML1918) effectively showed antimicrobial activity against several pathogenic organisms and can be employed as a suitable candidate for producing novel antimicrobial agents.