A new antibacterial and antioxidant S07-2 compound produced by Bacillus subtilis B38.

An antibacterial compound, S07-2, was purified to homogeneity by hydrophobic interaction, anion exchange, C18 reverse-phase and HS PEG HPLC. The molecular mass of S07-2 was 905.6 Da as determined by MS. The S07-2 compound was resistant to high temperatures (up to 100 degrees C) and could withstand a wide range of pH from 3 to 10. In addition, its antibacterial activity was preserved after treatment with proteases. Biochemical characterization revealed its cyclic peptide structure. This compound showed a bactericidal effect against important food-spoilage bacteria and food-borne pathogens including Listeria monocytogenes and Enterococcus faecalis with lethal concentration values of 62.5 microg mL(-1) and against Salmonella enteritidis at a concentration of 31.25 microg mL(-1). However, no cytotoxic effect against human erythrocytes was recorded. Furthermore, the S07-2 compound displayed a remarkable Fe(2+)-chelating activity (EC(50)=9.76 microg mL(-1)) and 1-diphenyl-2-picrylhydrazyl-scavenging capacity (IC(50)=65 microg mL(-1)). All these chemical and biological features make S07-2 a useful compound in the food industry as a natural preservative.