Phylogenomic insights, protease-related genes and protease of Ornithinibacillus proteolyticus sp. nov. isolated from fermented fish (Pla-ra).

A Gram-stain-positive, aerobic, spore-forming, moderately halophilic bacterium, designated JPR2-1T, was isolated from fermented fish (pla-ra). Optimal growth was observed at 30-37 °C, pH 7.0-7.5 and in the presence of 2-4% (w/v) NaCl. It contained l-Orn-d-Asp in the cell wall peptidoglycan and MK-7 as the major menaquinone. The predominant fatty acids were iso-C15:0, anteiso-C15 :0 and anteiso-C17:0. The polar lipid profile included diphosphatidylglycerol, phosphatidylglycerol, an unidentified phospholipid and an unidentified lipid. Strain JPR2-1ᵀ belonged to the genus Ornithinibacillus and was based on 16S rRNA gene sequence similarity of 99.76, 99.76, 98.50, 98.18 and 98.08% with 'Ornithinibacillus massiliensis' Marseille-P3601ᵀ, 'Ornithinibacillus hominis' BX22T, Ornithinibacillus scapharcae TW25T, Ornithinibacillus californiensis MB-9ᵀ and Ornithinibacillus bavariensis WSBC 24001ᵀ, respectively. The whole genome of strain JPR2-1T comprised 3,856,660 bp with 3,936 coding genes and a DNA G+C content of 37.3 mol%. The strain exhibited the average nucleotide identity values below 95% and lower than 70% of digital DNA-DNA hybridization in comparison to Ornithinibacillus species, except 'O. massiliensis' Marseille-P3601ᵀ and 'O. hominis' BX22T. This strain carried nine groups of intracellular hydrolytic genes (such as the rhomboid family and CAAX proteases) and three groups of extracellular proteolytic genes (the S8 family, the S9 family and zinc metallopeptidases). The highest specific activity of protease measured was 8.8 U mg-1 with the addition of 2.5% (w/v) NaCl. The results of this polyphasic study indicate that strain JPR2-1T is a novel species in the genus Ornithinibacillus, and the name Ornithinibacillus proteolyticus sp. nov. is proposed. The type strain is JPR2-1T (=JCM 32622T=KCTC 33904T=TISTR 2557T). In this study, 'O. massiliensis' and 'O. hominis' should be reclassified as a later heterotypic synonym of O. proteolyticus.