Abstract
Two novel endophytic bacterial strains, designated KSS8(T) and KSS12(T), were isolated from the stems and roots of sugarcane, respectively, collected in Nakhon Ratchasima, Thailand. They were Gram-stain-negative, aerobic, and rod-shaped. The strain KSS8(T) was a motile bacterium with a subpolar flagellum, while the strain KSS12(T) was non-motile. Strains KSS8(T) and KSS12(T) were closely related to Lichenicola cladoniae PAMC 26569(T) (97.3 and 95.6 %, respectively) and Lichenicoccus roseus KEBCLARHB70R(T) (97.2 and 95.8 %, respectively) based on the similarity on their 16S rRNA gene sequence. This similarity corresponded to their phylogenomic positions within the evolutionary radiation of the family Acetobacteraceae. The average nucleotide identities and digital DNA-DNA hybridization values between the genome sequences of the two strains and other genera were significantly lower than the defined threshold values of 95-96 % and 70 %, respectively, which are used for the delineation of prokaryotic species. Both strains contained summed feature 8 (C(18:1) ω7c and/or C(18:1) ω6c), C(16:0), C(19:0) cyclo ω8c, C(18:0), and C(18:1) 2OH as the predominant cellular fatty acids, but C(18:3) ω6c (6, 9, 12) were found only in strain KSS12(T). Based on phenotypic, chemotaxonomic, phylogenetic, and genomic analyses, these strains clearly represented two novel genera within the family Acetobacteraceae, for which the name Endosaccharibacter gen. nov., with the type species Endosaccharibacter trunci sp. nov. (type strain, KSS8(T) = TBRC 14669(T) = NBRC 115232(T) = KCTC 92115(T) = LMG 32414(T)) and the name Rhizosacchari bacter gen. nov., with the type species Rhizosaccharibacter radicis sp. nov. (type strain, KSS12(T) = TBRC 13066(T) = NBRC 114898(T) = KCTC 82433(T) = LMG 32137(T)) are proposed.