2002 Volume 48 Issue 5 Pages 269-279
A slightly halophilic, extremely halotolerant, alkaliphilic, and facultatively anaerobic rod bacterium was isolated from a decomposing marine alga collected in Okinawa, Japan. The isolate, designated O15-7T, was Gram-positive, endospore-forming, catalase-positive, menaquinone-7-possessing bacterium that is motile by peritrichous flagella. The isolate was an inhabitant of marine environments; the optimum NaCl concentration for growth was 0.75–3.0% (w/v) with a range of 0–22.0%, and the optimum pH was 7.0–8.5 with a range of 5.5–9.5. Catalase was produced in aerobic cultivation but not in anaerobic cultivation. Carbohydrate, sugar alcohol or a related carbon compound was required for growth. In aerobic cultivation, the isolate produced pyruvate, acetate and CO2 from glucose, and in anaerobic cultivation, it produced lactate, formate, acetate and ethanol with a molar ratio of approximately 2 : 1 : 1 for the last three products. No gas was produced anaerobically. Lactate yield per consumed glucose was markedly affected by the pH of the fermentation medium: 51% at pH 6.5 and 8% at pH 9.0. The cell-wall peptidoglycan contained meso-diaminopimelic acid. Phylogenetically, the isolate occupied an independent lineage within the group composed of the halophilic/halotolerant/alkaliphilic and/or alkalitolerant species in Bacillus rRNA group 1 with the highest 16S rRNA gene sequence similarity of 95.2% to the genus Gracilibacillus. For this isolate, Paraliobacillus ryukyuensis gen. nov., sp. nov. was proposed. The type strain, O15-7T (G+C=35.6 mol%), has been deposited in the DSMZ, IAM, NBRC, and NRIC (DSM 15140T=IAM 15001T=NBRC 10001T=NRIC 0520T).