Bacteriocin production by Leuconostoc citreum ST110LD isolated from organic farm soil, a promising biopreservative

Abstract

Aims: The objective of this study was to isolate a bacteriocin-producing strain and to characterize the expressed bacteriocin for the control of Listeria monocytogenes with aim of biopreservation application. Methods and Results: Soil samples from a Korean organic farm were subjected to microbiological analysis for isolation of potential bacteriocinogenic LAB, based on a three-level approach, using L. monocytogenes ATCC 15313 as an indicator test micro-organism. From a total of 17 isolates with inhibitory potential, seven were confirmed to be bacteriocin producers. The selected isolates were differentiated based on their morphology, catalase reaction, sugar fermentation profile obtained by API50CHL and by RAPD-PCR generating two unique profiles. One of the isolates, ST110LD, a specific strong producer of anti-Listeria bacteriocins (12 800 AU ml À1 ) was identified as Leuconostoc citreum. The proteinaceous nature of the inhibitory compound produced by Leuc. citreum ST110LD was confirmed through treatment with pepsin and a-chymotrypsin. Bacteriocin activity was observed to be not affected by the presence of milk, NaCl, SDS, Tween 80 or glycerol. Bacteriocin ST110LD effectively inhibited the growth of exponentially growing L. monocytogenes ATCC 15313 during a 10-h incubation period in BHI at 37°C. In addition, this bacteriocin showed specific inhibition of only Listeria spp., but did not inhibit the growth of beneficial cultures included in the microbial test panel for assessment of the spectrum of activity. Conclusions: Leuconostoc citreum ST110LD was evaluated as safe bacterium strain, producing bacteriocin with high specificity against listerial and enterococcal species. Specificity of producer strain and expressed bacteriocin can be explored in biopreservation of different fermented food products or applied in biotherapy of antibiotic resistant listerial or enterococcal infections. Significance and Impact of the Study: To the best of our knowledge, this is the first report of bacteriocin produced by Leuc. citreum strain with highly specific antimicrobial activity against Listeria sp. and Enterococcus sp.

Isolation and characterisation of the bacteriocin‐producingLeuconostoc citreumHW02from malts

“…citreum HW02 (Zangeneh et al ., 2020). Similar results showing the production of bacteriocin at the early exponential phase have been reported (Xiraphi et al ., 2008; Hwang et al ., 2018; Woo et al ., 2021). Maximal production of bacteriocin HW02 was detected at the middle of the stationary phase (at 12 h) as 320 AU mL −1 , and the pH was 4.51.…”

“…To the best of our knowledge, there are only three reports regarding Leu . citreum strains that produce bacteriocin (Chang et al ., 2007; Pujato et al ., 2014; Woo et al ., 2021).…”

Phylo-taxonogenomics of 182 strains of genusLeuconostocelucidates its robust taxonomy and biotechnological importance

“…Moreover, strains of genus Leuconostoc is reported to harbour several bacteriocins belonging to class IIa bacteriocins, leucocin H, mesentericin etc. [76–79] imparting antimicrobial activity against foodborne pathogens [80]. In-depth genomic investigation of bacteriocins and antimicrobial peptides are the need of the hour to explore the potential of the species of genus Leuconostoc .…”

A comparative study of antagonistic activity spectra of lactic acid bacteria isolated from fermented foods

“…A lot of information is available about LAB metabolites responsible for their antagonism. The production of bacteriocins is an inherent trait in many LAB strains belonging to different species and genera and many bacteriocins produced by LAB strains were isolated and described in-depth (Ahmad et al 2017;Ka skonien_ e et al 2017;Porto et al 2017;Woo et al 2021). Although by definition, bacteriocins act against closely related species, LAB strains exhibit a wide spectrum of antagonistic activity against Gram-positive and Gram-negative bacteria (Ahmad et al 2017;Todorov et al 2019).…”

“…2017; Woo et al . 2021). Although by definition, bacteriocins act against closely related species, LAB strains exhibit a wide spectrum of antagonistic activity against Gram‐positive and Gram‐negative bacteria (Ahmad et al .…”