PCR screening for the surfactin (sfp) gene in marine bacillus strains and its molecular characterization from Bacillus tequilensis NIOS11

The sfp gene responsible for surfactin production was screened from the DNA extracts of 37 Bacillus spp. whose identity was confirmed by 16S rRNA gene sequence analyses. PCR screening revealed amplification of sfp gene fragments in a total of 25 isolates. Several isolates belonging to Bacillus tequilensis were found to be positive for this gene. A gene fragment coding for the sfp gene was amplified and cloned from genomic DNA of the isolate B. tequilensis NIOS11. The cloned gene has an open reading frame of 675 bp coding for 224 amino acids with a theoretical molecular weight of 26,166.33 Da and a predicted isolectric point (pI) of 5.51. BLASTP analysis revealed 99% similarity to the earlier reported sfp gene of B. subtilis. Conserved domains of the sfp type PPTase family of proteins like P1a, P1b, P2, and P3 involved in biosynthesis of polyketides and nonribosomal peptides were observed. Phylogenetic analysis revealed a close relatedness of this gene with earlier reported sequences of B. subtilis. Results from the molecular characterization and substantial similarities with surfactins produced from B. subtilis make the B. tequilensis identified in this study a suitable candidate for exploring the potential of its application in the production of biosurfactants.