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

Sponge associated bacteria are a rich source of bioactive secondary metabolites. This study aims to isolate bacteria producing antimicrobial agents from a marine sponge, Callyspongia diffusa. A total of fifty-six bacteria were isolated and screened for antibacterial activity against multidrug resistant S. aureus. Based on the 16S rRNA sequence and phylogenetic analysis the antimicrobial producer strain MSI45 was identified as a novel Bacillus tequilensis. 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-a]pyrazine-1,4-dione,hexahydro. The extracted compound MSI45 showed a potent inhibitory effect on multidrug resistant S. aureus 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 Bacillus tequilensis MSI45 could have potent antimicrobial and antioxidant activity against S. aureus infection.