Description of Lactobacillus iwatensis sp. nov., isolated from orchardgrass (Dactylis glomerata L.) silage, and Lactobacillus backii sp. nov.

Two bacterial strains, designated IWT246(T) and IWT248, were isolated from orchardgrass (Dactylis glomerata L.) silage from Iwate prefecture, Japan, and examined for a taxonomic study. Both organisms were rod-shaped, Gram-stain-positive, catalase-negative, facultatively anaerobic and homofermentative. The cell wall did not contain meso-diaminopimelic acid and the major fatty acids were C18 : 1ω9c and C19 cyclo 9,10/:1. Comparative analyses of 16S rRNA, pheS and rpoA gene sequences revealed that these strains were novel and belonged to the genus Lactobacillus. Based on 16S rRNA gene sequence similarity, the isolates were most closely related to the type strains of the following members of the genus Lactobacillus: Lactobacillus coryniformis subsp. coryniformis (96.7 % similarity), L. coryniformis subsp. torquens (96.6 %), L. bifermentans (95.5 %) and L. rennini (94.1 %). However, the 16S rRNA gene sequences of both IWT246(T) and IWT248 were 99.7 % similar to that of 'Lactobacillus backi' JCM 18665; this name has not been validly published. Genotypic, phenotypic and chemotaxonomic analyses confirmed that these novel strains occupy a unique taxonomic position. DNA-DNA hybridization experiments demonstrated genotypic separation of the novel isolates from related Lactobacillus species. The name Lactobacillus iwatensis sp. nov. is proposed for the novel isolates, with strain IWT246(T) ( = JCM 18838(T) = DSM 26942(T)) as the type strain. Our results also suggest that 'L. backi' does represent a novel Lactobacillus species. The cells did not contain meso-diaminopimelic acid in their cell-wall peptidoglycan and the major fatty acids were C16 : 0, C19 cyclo 9,10/:1 and summed feature 10 (one or more of C18 : 1ω11c, C18 : 1ω9t, C18 : 1ω6t and unknown ECL 17.834). We therefore propose the corrected name Lactobacillus backii sp. nov., with the type strain JCM 18665(T) ( = LMG 23555(T) = DSM 18080(T) = L1062(T)).