Amphibacillus iburiensis sp. nov., an alkaliphile that reduces an indigo dye.

An indigo-reducing alkaliphilic strain, designated strain N314(T), was isolated from a fermented polygonum indigo (Polygonum tinctorium Lour.) liquor sample, aged for 10 months, that was obtained from Date City, Iburi Branch, Hokkaido, Japan. The 16S rRNA gene sequence phylogeny suggested that strain N314(T) is a member of the genus Amphibacillus, with the closest relatives being Amphibacillus indicireducens (98.9 % similarity to the type strain) and Amphibacillus xylanus (98.0 % similarity to the type strain), the only species with 16S rRNA gene sequence similarities higher than 97 % to strain N314(T). The cells of the isolate stained Gram-positive and were facultatively anaerobic, straight rods that were motile by means of peritrichous flagella. The strain grew at 26-39 °C with optimum growth at 36 °C. It grew at pH 8.0-9.1, with optimum growth at pH 8.9-9.1. No isoprenoid quinone was detected, and the DNA G+C content was 38.4 mol%. The whole-cell fatty acid profile consisted mainly of iso-C15 : 0 and anteiso-C15 : 0. Analysis of DNA-DNA hybridization with the type strains of A. indicireducens and A. xylanus revealed 29±2 % and 10±2 % relatedness, respectively. Owing to differences in phenotypic characteristics from reported species of the genus A. and results of phylogenetic analyses based on 16S rRNA gene sequences and DNA-DNA relatedness data, the isolate merits classification within a novel species, for which the name Amphibacillus iburiensis sp. nov. is proposed. The type strain is N314(T) ( = JCM 18529(T) = NCIMB 14823(T)).