Screening and identification of an epiphytic bacterium producing lipopeptides based on NRPS gene

In this study, five epiphytic bacteria were isolated from " summer black" grapes using plate streaking and slant culture methods. After extraction of DNA, 16 S r DNA from the five strains were amplified for sequence homology analysis, and the phylogenetic trees were constructed with MEGA 6.0.The results showed that the five strains were characterized as Klebsiella pneumoniae, Bacillus subtilis, Kocuria marina, Bacillus aerophilus, Paenibacillus agaridevorans, respectively. On this basis, the strain PTWA2 was screened with the non-ribosomal peptide compounds synthetase (NRPS) gene. After construting the NRPS phylogenetic tree, the results showed that the PTWA2 was capable of producing lipopeptide.As a result, a pure compound was obtained from the fermentation product of the PTWA2 by solvent extraction, silica gel column chromatography and Sephedex LH-20 chromatography and its chemical sturture was identified as surfactin A by physiochemical analysis and spectroscopic techniques.The study highlights new research methods and theoretical basis for target-screening strains which produced cyclic lipopeptide.