Identification and biochemical characteristics of lipopeptides from Bacillus mojavensis A21

• Identification of NRPS genes encoding both surfactin and fengycin from Bacillus mojavensis A21.
• Coproduction of surfactin and fengycin was confirmed using MALDI-TOF MS.
• MALDI-TOF-TOF revealed the presence of pumilacidin isoforms.
• Lipopeptide mixture showed potent antimicrobial and antifungal activity.
• Its activity was highly stable at extremes pH, temperature and proteases effect.

This study reports the potential of a marine bacterium, Bacillus mojavensis A21, to produce lipopeptide biosurfactants. The crude lipopeptide mixture was found to be very effective in reducing surface tension to 31 mN m−1. PCR experiments using degenerate primers revealed the presence of nonribosomal peptide synthetases genes implied in the biosyntheses of fengycin and surfactin. Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS) performed on whole cells of B. mojavensis A21 confirmed the presence of lipopeptides identified as members of surfactin and fengycin families. Further, a detailed analysis performed by MALDI-TOF-TOF revealed the presence of pumilacidin compounds. The crude lipopeptide mixture was tested for its inhibitory activity against Gram-positive and Gram-negative bacteria, and fungal strains. It was found to display significant antimicrobial activity. Strain A21 lipopeptide mixture was insensitive to proteolytic enzymes, stable between pH 3.0 and 11.0, and resistant to high temperature. Production of lipopeptides is a characteristic of several Bacillus species, but to our knowledge this is the first report involving identification of pumilacidin, surfactin and fengycin isoforms in a B. mojavensis strain.