Lactobacillus paracollinoides sp. nov., isolated from brewery environments

This study describes Lactobacillus paracollinoides sp. nov., a novel bacterial species isolated from brewery environments. Three strains (LA2T, LA7, and LA8) were initially recovered from Japanese breweries and characterized using phylogenetic analysis, DNA-DNA hybridization, and biochemical testing. The strains are Gram-positive, facultatively anaerobic, heterofermentative rods that lack catalase activity. Phylogenetic analysis based on 16S rRNA gene sequences revealed approximately 99% similarity to Lactobacillus collinoides. However, DNA-DNA relatedness values (46.8-57.6%) with L. collinoides were significantly below the species delineation threshold. The novel strains differ from L. collinoides by their inability to ferment D-fructose and, critically, their strong beer-spoilage ability. The new species forms visible turbidity in commercial beer within 7 days, comparable to Lactobacillus brevis, the most serious beer-spoilage bacterium. In contrast, L. collinoides strains do not grow in beer. The type strain LA2T has a DNA G+C content of 44.8 mol%, consistent with the genus Lactobacillus. The three brewery isolates share identical ribotypes and are distinguishable from L. collinoides on multiple criteria, justifying classification as a distinct species.

Key findings

• Lactobacillus paracollinoides represents a novel species closely related to L. collinoides but distinct based on DNA-DNA hybridization values below the species threshold
• Unlike L. collinoides, L. paracollinoides exhibits strong beer-spoilage ability, forming visible turbidity within 7 days, comparable to L. brevis
• L. paracollinoides differs from L. collinoides by inability to ferment D-fructose and variable L-arabinose utilization
• The type strain LA2T has a G+C content of 44.8 mol% and was isolated from brewery environments in Japan