Bacillus fermenti sp. nov., an indigo-reducing obligate alkaliphile isolated from indigo fermentation liquor for dyeing.

The indigo-reducing, facultatively anaerobic and obligately alkaliphilic strains Bf-1, Bf-2 and Bf-4 were isolated from an indigo fermentation liquor used for dyeing, which uses sukumo [composted Polygonum indigo (Polygonum tinctorium Lour.) leaves] as a basic ingredient and was obtained from a craft centre in Date City, Hokkaido, Japan. The 16S rRNA gene sequence analyses indicated that the closest neighbours of strain Bf-1 are Bacillus maritimus DSM 100413 (98.3 % 16S rRNA gene sequence similarity), Bacillus persicus DSM 25386 (98.2 %) and Bacillus rigiliprofundi LMG 28275 (97.7 %). The 16S rRNA gene sequence of strain Bf-1 was almost identical to the sequences of strains Bf-2 and Bf-4 (99.9 %). Cells of strain Bf-1 stained Gram-positive and formed straight rods that achieved motility through a pair of subpolar flagella. Strain Bf-1 grew at temperatures of between 15 and 45 °C with optimum growth at 33‒40 °C. The strain grew in the pH range of pH 8‒12, with optimum growth at pH 10. The isoprenoid quinone detected was menaquinone-7 (MK-7), and the DNA G+C content was 41.7 %. The whole-cell fatty acid profile mainly (>10 %) consisted of iso-C15 : 0 and iso-C16 : 0. Phylogenetically related neighbours, although demonstrating high 16S rRNA gene sequence similarity (>97.6 %) with strain Bf-1, exhibited less than 9 % relatedness in DNA-DNA hybridization experiments. Based on evidence from this polyphasic study, the isolates represent a novel species, for which the name Bacillus fermenti sp. nov. is proposed. The type strain of this species is Bf-1 (=JCM 31807=NCIMB 15079).