A psychrotolerant, obligately alkaliphilic bacterium, IDR2-2^T, which is able to reduce indigo dye was isolated from a fermented polygonum indigo (Polygonum tinctorium Lour.) produced in Date, Hokkaido, using a traditional Japanese method. The isolate grew at pH 9–12 but not at pH 7–8. It was a Gram-positive, facultatively anaerobic, straight rod-shaped bacterium with peritrichous flagella. The isolate grew in 0–17 % (w/v) NaCl but not at NaCl concentrations higher than 18 % (w/v). Its major cellular fatty acids were C_14 : 0, C_16 : 0, C_16 : 19c and C_18 : 19c, and its DNA G+C content was 40·6 mol%. dl-lactic acid was the major end-product from d-glucose. No quinones could be detected. The peptidoglycan type was A4β, Orn–d-Glu. A phylogenetic analysis based on 16S rRNA gene sequence data indicated that strain IDR2-2^T is a member of the genus Alkalibacterium. DNA–DNA hybridization revealed low relatedness (less than 25 %) between the isolate and two phylogenetically related strains, Alkalibacterium olivapovliticus and Marinilactibacillus psychrotolerans. On the basis of phenotypic characteristics, phylogenetic data and DNA–DNA relatedness data, the isolate merits classification as a novel species, for which the name Alkalibacterium psychrotolerans sp. nov. is proposed. The type strain is IDR2-2^T (=JCM 12281^T=NCIMB 13981^T).

A facultatively psychrophilic bacterium, strain MD17T, which hydrolyses lipids at 5 °C, was isolated from the Monbetsu coast of the Okhotsk Sea in Hokkaido, Japan, when ice carried by the cold current came to the area. The isolate is an aerobic, non-motile coccobacillus that reduces nitrate to nitrite and hydrolyses Tweens 20, 40, 60 and 80, but not gelatin, DNA or alginic acid. The isolate grows at 0 °C, but not at temperatures higher than 36 °C; its optimum growth temperature is 25 °C. It grows in the presence of 0–10 % NaCl. Its major isoprenoid quinone is ubiquinone-8 (Q-8) and its DNA G+C content is 46·7 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain MD17T is closely related to Psychrobacter glacincola DSM 12194T (99·0 % similarity) and Psychrobacter immobilis DSM 7229T (98·7 % similarity). DNA–DNA hybridization revealed 45·9 % relatedness between strain MD17T and P. immobilis ATCC 43116T and 33·4 % between strain MD17T and P. glacincola ATCC 700754T. Based on physiological and biochemical characteristics, phylogenetic position (as determined by 16S rRNA gene sequence analysis) and DNA–DNA relatedness, it is concluded that the isolate should be designated as a novel species, for which the name Psychrobacter okhotskensis sp. nov. is proposed. The type strain is MD17T (=NCIMB 13931T=JCM 11840T).

A novel alkaliphile was isolated from a drain of a fish processing plant. The isolate grew at a pH range of 7–10. Cells were Gram-positive, facultatively aerobic, motile rods with peritrichous flagella. Colonies were orange or yellow in colour. Catalase and oxidase reactions were positive. The isolate grew in 0–12 % NaCl but not above 15 % NaCl. Its cell extract exhibited 567 times higher catalase activity than an Escherichia coli cell extract. The major cellular fatty acids were iso-C_13 : 0, anteiso-C_13 : 0, iso-C_15 : 0, iso-C_16 : 0, iso-C_17 : 0, anteiso-C_17 : 0 and iso-C_17 : 1. Its DNA G+C content was 46·7 mol%. Phylogenetic analysis based on 16S rRNA gene sequencing and chemotaxonomic data indicated that strain T-2-2^T is a member of the genus Exiguobacterium. DNA–DNA hybridization revealed a low relatedness of the isolate to several phylogenetic neighbours (less than 25 %). On the basis of phenotypic characteristics, phylogenetic data and DNA–DNA relatedness data, the isolate merits classification as a novel species, for which the name Exiguobacterium oxidotolerans sp. nov. is proposed. The type strain is T-2-2^T (=JCM 12280^T=NCIMB 13980^T).

Indigo-reducing, obligately alkaliphilic strains A11^T, F11 and F12 were isolated from indigo fermentation liquor obtained from Tokushima Prefecture, Shikoku, Japan. The isolates grew at pH 9.0–12.3, but not at pH 7.0–8.0. The optimum pH range for growth was 9.5–11.5. They were Gram-negative, facultatively anaerobic, rod-shaped strains with peritrichous flagella. The isolates grew in 0–14 % (w/v) NaCl, with optimum growth at 1–11 %. They grew at temperatures of 15–35 °C with optimum growth at around 20–30 °C. dl-Lactate was the major end product from d-glucose. No quinones were detected. The peptidoglycan type was A4α, l-Lys (l-Orn)–d-Asp. The major cellular fatty acids were C_16 : 0, C_16 : 17c and C_18 : 19c. The DNA G+C contents were 47.0–47.8 mol%. Phylogenetic analysis based on 16S rRNA gene sequence data indicated that the isolates belong to the genus Alkalibacterium. DNA–DNA hybridization revealed low relatedness values between the isolates and the three phylogenetically most closely related species, Alkalibacterium olivapovliticus, Alkalibacterium psychrotolerans and Alkalibacterium iburiense (<41 %). On the basis of phenotypic characteristics, including hydrolysis of cellulose and fermentation of carbohydrates, and chemotaxonomic characteristics, phylogenetic data and DNA–DNA relatedness data, it is concluded that the isolates merit classification as representatives of a novel species of the genus Alkalibacterium, for which the name Alkalibacterium indicireducens sp. nov. is proposed. The type strain of this species is A11^T (=JCM 14232^T=NCIMB 14253^T).

A halotolerant, obligately alkaliphilic bacterium, R-2^T, was isolated from the skin of a rainbow trout (Oncorhynchus mykiss), a freshwater fish. The strain is Gram-positive, ferments several carbohydrates, is rod-shaped and motile by peritrichous flagella and produces ellipsoidal spores. The isolate grows at pH 9–10 but not at pH 7–8. This micro-organism grows in 0–22 % (w/v) NaCl at pH 10. Its major cellular fatty acids are iso-C_15 : 0, anteiso-C_15 : 0 and anteiso-C_17 : 0, the major isoprenoid quinone is MK-7 and the DNA G+C content is 38·5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicates that strain R-2^T is a member of the genus Oceanobacillus. DNA–DNA hybridization reveals low relatedness between the isolate and Oceanobacillus iheyensis (21·0 %). On the basis of phenotypic characteristics, phylogenetic data and DNA–DNA relatedness data, the isolate should be designated as a novel species, for which the name Oceanobacillus oncorhynchi sp. nov. is proposed. The type strain is R-2^T (=JCM 12661^T=NCIMB 14022^T).

Indigo fermentation, which depends on the indigo-reducing action of microorganisms, has traditionally been performed to dye textiles blue in Asia as well as in Europe. This fermentation process is carried out by naturally occurring microbial communities and occurs under alkaline, anaerobic conditions. Therefore, there is uncertainty regarding the fermentation process, and many unknown microorganisms thrive in this unique fermentation environment. Until recently, there was limited information available on bacteria associated with this fermentation process. Indigo reduction normally occurs from 4 days to 2 weeks after initiation of fermentation. However, the changes in the microbiota that occur during the transition to an indigo-reducing state have not been elucidated. Here, the structural changes in the bacterial community were estimated by PCR-based methods. On the second day of fermentation, a large change in the redox potential occurred. On the fourth day, distinct substitution of the genus Halomonas with the aerotolerant genus Amphibacillus was observed, corresponding to marked changes in indigo reduction. Under open-air conditions, indigo reduction during the fermentation process continued for 6 months on average. The microbiota, including indigo-reducing bacteria, was continuously replaced with other microbial communities that consisted of other types of indigo-reducing bacteria. A stable state consisting mainly of the genus Anaerobacillus was also observed in a long-term fermentation sample. The stability of the microbiota, proportion of indigo-reducing microorganisms, and appropriate diversity and microbiota within the fluid may play key factors in the maintenance of a reducing state during long-term indigo fermentation. Although more than 10 species of indigo-reducing bacteria were identified, the reduction mechanism of indigo particle is riddle. It can be predicted that the mechanism involves electrons, as byproducts of metabolism, being discarded by analogs mechanisms reported in bacterial extracellular solid Fe³⁺ reduction under alkaline anaerobic condition.