Researchers isolated five strains of lactic acid bacteria from flowers collected in Japanese mountainous regions (Oze National Park, Iizuna mountain, and Nikko area) between 2006-2009. These isolates shared nearly identical 16S rRNA gene sequences (99.6-100% similar) and showed low similarity to known Lactobacillus species, with the closest relatives being L. hilgardii, L. kefiri, L. composti, and L. buchneri (all <93% similarity). Phylogenetic analysis using 16S rRNA, rpoA, and pheS genes confirmed these isolates represent a novel species. The bacteria are Gram-positive, catalase-negative, homofermentative rods that produce L-lactic acid. They utilize a narrow range of carbohydrates, primarily glucose and fructose, and grow optimally at 30°C. Based on phenotypic characteristics and genetic data, the researchers propose the name Lactobacillus floricola sp. nov., with strain Ryu1-2T designated as the type strain. The discovery adds to the known diversity of lactic acid bacteria naturally present in floral environments.

Key findings

• Five Lactobacillus isolates from Japanese mountain flowers represent a novel species, L. floricola sp. nov., with <93% 16S rRNA similarity to known species
• The isolates are homofermentative, producing L-lactic acid from glucose and fructose with a narrow carbohydrate utilization profile
• Phylogenetic analysis of 16S rRNA, rpoA, and pheS genes confirms the isolates form a distinct clade separate from related Lactobacillus species
• Bacteria grow optimally at 20-30°C and were detected in high abundance (10⁴-10⁸ colonies) in multiple flower samples, indicating they are major inhabitants of floral microbiota