Discovery and characterisation of circular bacteriocin plantacyclin B21AG from Lactiplantibacillus plantarum B21

Abstract

Lactiplantibacillus plantarum B21 isolated from Vietnamese sausage ( nem chua ) has previously displayed broad antimicrobial activity against Gram-positive bacteria including foodborne pathogens Listeria monocytogenes and Clostridium perfringens . This study successfully identified the antimicrobial agent as plantacyclin B21AG, a 5668 Da circular bacteriocin demonstrating high thermostability, resistance to a wide range of pH, proteolytic resistance and temporal stability. We report a reverse genetics approach to identify and characterise plantacyclin B21AG from first principles. The bacteriocin was purified from culture supernatant by a three-step process consisting of concentration, n-butanol extraction and cation exchange chromatography. A de novo peptide sequencing using LC-MS/MS techniques identified two putative peptide fragments which were mapped to the genome sequence of L. plantarum B21. This revealed an ORF corresponding to a putative circular bacteriocin with a 33-amino acid leader peptide and a 58-amino acid mature peptide encoded on a native plasmid pB21AG01. The bacteriocin is shown to be a small cationic predominantly α-helical protein (69%). The corresponding gene cluster, consisted of seven genes associated with post-translational circularisation, immunity and secretion. Whilst plantacyclin B21AG is 86% identical to the newly published plantaricyclin A it is more highly cationic having a net charge of +3 due to an additional basic residue in the putative membrane interaction region. This and other substitutions may well go some way to explaining functional differences. The robust nature of plantacyclin B21AG, its antimicrobial activity and associated machinery for cyclisation make it an interesting biotechnological target for development, both as a food-safe antimicrobial or potentially a platform technology for recombinant protein circularisation.

Antimicrobial property of recombinant Lactolisterin BU in vitro and its initial application in pork refrigerated storage

“…4D, and antibacterial activity decreased compared with that of the control. These results agreed with the L. lactis derived Lactolisterin BU and most bacteriocins, including BAC-IB17 [22], BaCf3 [23], and plantacyclin B21AG [24], which were thermostable. These results showed that rLactolisterin BU could be used in food products processed with high temperature, addition of acid or base, and salinization.…”

Natural Compounds With Antimicrobial and Antiviral Effect and Nanocarriers Used for Their Transportation

“…Lactobacillus plantarum B21 isolated from Vietnamese sausage (nem chua) has previously shown broad antimicrobial activity against Gram-positive bacteria, including foodborne pathogens Listeria monocytogenes and Clostridium perfringens . In this study, the antimicrobial agent was successfully identified as plantacyclin B21AG, a circular bacteriocin with 5668 Da that exhibits high thermostability, resistance to a wide pH range, proteolytic resistance, and temporal stability ( Golneshin et al, 2020 ). Its antimicrobial spectrum of activity included killing activity against closely related Lactobacillus species and foodborne pathogens Clostridium perfringens and Listeria monocytogenes .…”

Lactic Acid Bacteria Diversity and Characterization of Probiotic Candidates in Fermented Meats

“…Different strains of L. plantarum have been reported to produce bacteriocins with varied structural properties and antagonistic activities. For instance, L. plantarum B21 was previously demonstrated to be effective against a broad range of LAB and a few non-LAB species ( Listeria monocytogenes and Clostridium perfringens ) [ 69 ], whereas L. plantarum LPL-1 was effective against a broad range of non-LAB species ( L. monocytogenes , S. aureus , E. faecalis , B. amyloliquefaciens and B. pumilus) and several strains of Lactococcus and Lactobacillus [ 70 ]. L. plantarum NI326 produces the cyclic bacteriocin plantaricyclin A, which shared 99 to 100% similarity to the bacteriocin encoding cluster of L. plantarum 13A, 38I and 41G isolated in the present study ( Figure S3 ), that is effective against some strains of Lactococcus , L. bulgaricus and Alicyclobacillus acidoterrestris but is not effective against L. plantarum , L. brevis , Pediococcus , Listeria , Escherichia , Staphylococcus , Streptococcus , Klebsiella and Bacillus [ 71 ].…”