Whole-genome safety assessment of Loigolactobacillus coryniformis WBB05 and identification of a candidate gene for aerobic reuterin production.

Abstract

This study reports on the safety profile of Loigolactobacillus coryniformis WBB05 for food industry applications and identifies glycerol-3-phosphate oxidase (GlpO) as a candidate gene associated with aerobic reuterin production. The safety of L. coryniformis WBB05 was evaluated through whole-genome sequencing, phenotypic analysis of haemolytic activity and determination of minimum inhibitory concentrations (MICs) of antibiotics. Comparative genomic analysis was performed to identify candidate genetic determinants for aerobic reuterin production. The draft genome (2.83 Mb, 179 contigs) harboured no known virulence factors, acquired antimicrobial resistance (AMR) genes or biogenic amine biosynthetic genes. Prophage analysis identified only one incomplete prophage region, and four CRISPR-Cas systems (212 spacers) were consistent with phage defence capacity. Secondary metabolite analysis revealed biosynthetic gene clusters encoding a coagulin-like bacteriocin. No β-haemolytic activity was observed. The MICs of all antibiotics tested were below the European Food Safety Authority cut-off values except for kanamycin (128 mg/L), although no acquired AMR genes were detected. Comparative genomic analysis revealed that L. coryniformis WBB05 possesses two putative copies of GlpO, a gene not detected in publicly available genomes of Limosilactobacillus reuteri, which produces reuterin only under anaerobic conditions. These findings support the use of L. coryniformis WBB05 as a safe adjunct culture for dairy applications and highlight GlpO as a candidate determinant of aerobic reuterin production. Further studies comparing GlpO-positive and GlpO-negative strains under aerobic and anaerobic conditions are warranted to confirm the role of GlpO.