Bioinformatics analysis of purified and identified novel bacteriocin‐like inhibitory substances produced by Streptomyces sp.

Abstract

SummaryBacteriocins are antimicrobial peptides synthesised ribosomally by bacteria that can be used as natural preservatives. One potential bacteriocin‐producing bacteria that has yet to be widely studied is Streptomyces sp. Bioinformatics analysis has been conducted on the purified and identified bacteriocin‐like inhibitory substances (BLIS) produced by Streptomyces sp. The BLIS fraction, purified by reversed‐phase high‐performance liquid chromatography, showed significantly increased specific activities against E. coli, L. monocytogenes, S. aureus and S. typhimurium (1.2–189.4 folds). Identification of four purified BLIS fractions using HR‐LC‐ESI‐MS/MS revealed molecular mass from 1287.51 to 1812.85 Da with the sequences of TAEAEAAEGAEEAAP (fraction AS531), TQGGINANKTGSQGYG (fraction AS822), SGGYGGMGAGGIGGQRSGPQ (fraction AS857) and PGGAKGGFGGGGRPGGQGMPGG (fraction AS1121). These peptide sequences have a minimum of 2 hydrophobic amino acids, a net charge of −4 to +2, an isoelectric point of 2.68–11.71 and a hydrophobicity of 20.44–27.46 kcal mol−1. The results of molecular docking analysis between purified BLIS and the penicillin‐binding protein 3 (PBP‐3) receptor by methicillin‐resistant Staphylococcus aureus (MRSA) also showed that four fractions had low binding energy (−7.5 to −8.1 kcal mol−1) with 17–25 hydrogen bonds and distances <4 Å. Furthermore, in vitro characterisation revealed that the four purified‐BLIS have a low to moderate LC50 (68.81–200.35 μgmL−1) against A. salina and the ability to maintain 50% antibacterial activity against E. coli up to 100 °C for 30 min and in the pH range of 2.0–8.0, especially fractions AS531 and AS822. Based on the antibacterial spectrum, physicochemical characteristics and peptide sequence, BLIS produced by Streptomyces sp., is a novel bacteriocin with promising applications as a food preservative.