An antibiotic agent pyrrolo[1,2-<i>a</i>]pyrazine-1,4-dione,hexahydro isolated from a marine bacteria <i>Bacillus tequilensis</i> MSI45 effectively controls multi-drug resistant <i>Staphylococcus aureus</i>

Abstract

Sponge associated bacteria are a rich source of bioactive secondary metabolites. This study aims to isolate bacteria producing antimicrobial agents from a marine sponge, <i>Callyspongia diffusa</i>. A total of fifty-six bacteria were isolated and screened for antibacterial activity against multidrug resistant <i>S. aureus</i>. Based on the 16S rRNA sequence and phylogenetic analysis the antimicrobial producer strain MSI45 was identified as a novel <i>Bacillus tequilensis</i>. The culture conditions of strain MSI45 were optimized to enhance the yield of the antimicrobial compound. The antimicrobial compound was purified using a silica gel column chromatography and high performance liquid chromatography. On the basis of spectroscopic analysis such as FT-IR, NMR and GC-MS, the bioactive metabolite was identified as pyrrolo[1,2-<i>a</i>]pyrazine-1,4-dione,hexahydro. The extracted compound MSI45 showed a potent inhibitory effect on multidrug resistant <i>S. aureus</i> with an MIC of 15 ± 0.172 mg L^-1 and MBC of 20 ± 0.072 mg L^-1. The compound was non-hemolytic and showed high antioxidant activity. The antioxidant activity may increase the efficacy and safety of the molecule in drug development. Hence, this compound produced by <i>Bacillus tequilensis</i> MSI45 could have potent antimicrobial and antioxidant activity against <i>S. aureus</i> infection.