Five strains (Mizu2-1 T , Gon2-7, Koba6-1, Koyu2-2 and Miya2-2) of lactic acid bacteria (LAB) were isolated from flowers in Oze National Park, Japan, using anaerobic cultivation. The five isolates were found to share identical 16S rRNA gene sequences. The isolates exhibited low levels of 16S rRNA gene sequence similarity to known LAB; the closest recognized relatives of strain Mizu2-1 T were the type strains of Lactobacillus kunkeei (94.9 %), Lactobacillus kefiri (94.1 %) and Lactobacillus buchneri (93.9 %). Comparative analyses of rpoA and pheS gene sequences demonstrated that the novel isolates did not show significant relationships to other Lactobacillus species. The strains were Gram-stain-positive, catalase-negative and heterofermentative. Anaerobic growth was better than aerobic growth. The isolates utilized a narrow range of carbohydrates as sources of carbon and energy, including glucose and fructose. On the basis of phenotypic characteristics and phylogenetic data, the isolates represent a novel species of the genus Lactobacillus, for which the name Lactobacillus ozensis sp. nov. is proposed. The type strain is Mizu2-1 T (5JCM 17196 T 5DSM 23829 T ).During our studies on the distribution of anaerobes in flowers, we have isolated several species of lactic acid bacteria (LAB) from mountain flowers in Japan. We recently reported the isolation of a novel LAB, Lactobacillus floricola, from a mountainous area (Kawasaki et al., 2011). L. floricola showed quite low 16S rRNA gene sequence similarity to known LAB, and also showed a narrow range of carbohydrate utilization, using only glucose and fructose. Here, we report the isolation of further isolates that exhibit low 16S rRNA gene sequence similarity to known LAB and show a narrow range of carbohydrate utilization. During the course of our investigations of anaerobes in flowers from several mountainous areas in Japan since 2006, the novel species described in this study has been isolated only from the area of Oze National Park.Flowers were collected from Oze National Park in [2008][2009]. Flower samples were collected using autoclaved forceps and transferred immediately to sterile tubes. Bacteria were cultivated on MRS agar (Difco) containing 5.0 g calcium carbonate and 15 g agar l 21 at 20-30 u C under anaerobic conditions. After isolation, strains were maintained in MRS broth. The origins of the isolates are shown in Supplementary Fig. S1. The proposed type strain Mizu2-1 T was isolated from a flower of Inula ciliaris var. glandulosa, a chrysanthemum (Japanese common name, oze-mizugiku), that was collected in August 2008. A large number of colonies (10 4 -10 8 colonies per flower) were obtained, and the 16S rRNA gene sequences of randomly selected colonies suggested that these isolates represent the most abundant species in each flower (data not shown).Morphological, physiological and biochemical characteristics were determined according to Okada et al. (1992), Holdeman et al. (1977) and Gerhardt et al. (1981), as described previously (Kawasaki et al., 2011...