%0 Journal Article
%T Characterization of two antimicrobial peptides produced by a halotolerant Bacillus subtilis strain SK.DU.4 isolated from a rhizosphere soil sample
%A Piyush Baindara
%A Santi M Mandal
%A Niharika Chawla
%A Pradip Kumar Singh
%A Anil Kumar Pinnaka and Suresh Korpole
%J AMB Express
%D 2013
%I Springer
%R 10.1186/2191-0855-3-2
%X A bacterial strain producing two antimicrobial peptides was isolated from a rhizosphere soil sample and identified as Bacillus subtilis based on both phenotypic and 16S rRNA gene sequence phylogenetic analysis. It grew optimally up to 14% NaCl and produced antimicrobial peptide within 24 h of growth. The peptides were purified using a combination of chemical extraction and chromatographic techniques. The MALDI-TOF analysis of HPLC purified fractions revealed that the strain SK.DU.4 secreted a bacteriocin-like peptide with molecular mass of 5323.9 Da and a surface-active lipopeptide (m/z 1056 Da). The peptide mass fingerprinting of low-molecular-weight bacteriocin exhibited significant similarity with stretches of secreted lipoprotein of Methylomicrobium album BG8 and displayed 70% sequence coverage. MALDI MS/MS analysis elucidated the lipopeptide as a cyclic lipopeptide with a ¦Â-hydroxy fatty acid linked to Ser of a peptide with seven ¦Á-amino acids (Asp-Tyr-Asn-Gln-Pro-Asn-Ser) and assigned it to iturin-like group of antimicrobial biosurfactants. However, it differed in amino acid composition with other members of the iturin family. Both peptides were active against Gram-positive bacteria, suggesting that they had an additive effect.
%K Bacillus
%K Antimicrobial peptide
%K Lipopeptide
%K Chromatography
%K RP-HPLC
%K MALDI
%U http://www.amb-express.com/content/3/1/2/abstract