ABSTRACT
Two Gram-stain-negative, rod-shaped bacteria, designated as strains KJ10-1T and KJ40-1T, were isolated from marine brown algae. Both strains were catalase-positive, oxidase-positive, and facultative aerobic. Strain KJ10-1T exhibited optimal growth at 25â°C, pH 7.0, and 3â% NaCl, whereas strain KJ40-1T showed optimal growth at 25â°C, pH 7.0, and 2â% NaCl. The respiratory quinones of strain KJ10-1T were ubiquinone-8, ubiquinone-7, menaquinone-7, and methylated menaquinone-7, while the respiratory quinone of strain KJ40-1T was only ubiquinone-8. As major fatty acids, strain KJ10-1T contained C16â:â0, C17â:â1 ω8c, iso-C15â:â0, and summed feature 3 (C16â:â1 ω7c and/or C16â:â1 ω6c) and strain KJ40-1T contained C16â:â0 and summed features 3 and 8 (C18â:â1 ω7c and/or C18â:â1 ω6c). The major polar lipids in strain KJ10-1T were phosphatidylethanolamine, phosphatidylglycerol, and an unidentified aminolipid, whereas those in strain KJ40-1T were phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. The DNA G+C contents of strains KJ10-1T and KJ40-1T were 42.1 and 40.8âmol%, respectively. Based on 16S rRNA gene sequences, strains KJ10-1T and KJ40-1T exhibited the closest relatedness to Shewanella saliphila MMS16-UL250T (98.6â%) and Vibrio rumoiensis S-1T (95.4â%), respectively. Phylogenetic analyses, based on both 16S rRNA and 92 housekeeping genes, showed that the strains formed distinct phylogenic lineages within the genera Shewanella and Vibrio. Digital DNA-DNA hybridization and orthologous average nucleotide identity values between strain KJ10-1T and other Shewanella species, as well as between strain KJ40-1T and other Vibrio species, were below the thresholds commonly accepted for prokaryotic species delineation. Based on the phenotypic, chemotaxonomic, and phylogenetic data, strains KJ10-1T and KJ40-1T represent novel species of the genera Shewanella and Vibrio, respectively, for which the names Shewanella phaeophyticola sp. nov. and Vibrio algarum sp. nov. are proposed, respectively. The type strains of S. phaeophyticola and V. algarum are KJ10-1T (=KACC 22589T=JCM 35409T) and KJ40-1T (=KACC 22588T=JCM 35410T), respectively.
Subject(s)
Bacterial Typing Techniques , Base Composition , DNA, Bacterial , Fatty Acids , Phaeophyceae , Phylogeny , RNA, Ribosomal, 16S , Sequence Analysis, DNA , Shewanella , Ubiquinone , Vibrio , Vitamin K 2 , RNA, Ribosomal, 16S/genetics , DNA, Bacterial/genetics , Vibrio/genetics , Vibrio/classification , Vibrio/isolation & purification , Ubiquinone/analogs & derivatives , Shewanella/genetics , Shewanella/isolation & purification , Shewanella/classification , Phaeophyceae/microbiology , Vitamin K 2/analogs & derivatives , Phospholipids , Nucleic Acid Hybridization , Seawater/microbiologyABSTRACT
Two Gram-stain-negative, obligately aerobic, motile rod bacteria, designated as G2-5T and G20-9T, exhibiting catalase- and oxidase-positive activities, were isolated from the phycosphere of a Chondrus species, a marine red alga. Strain G2-5T exhibited optimal growth at 30â°C and pH 5.0-6.0 and in the presence of 0.5-1.0% NaCl. In contrast, strain G20-9T demonstrated optimal growth at 25â°C and pH 6.0 and in the presence of 0.5-1.5% NaCl. Both strains contained ubiquinone-10, summed feature 8 (C18â:â1 ω7c and/or C18â:â1 ω6c), C18â:â0 and 11-methyl-C18â:â1 ω7c, and diphosphatidylglycerol and phosphatidylglycerol as the major respiratory isoprenoid quinone, cellular fatty acids and polar lipids, respectively. The genomic DNA G+C contents were 57.2âmol% for strain G2-5T and 57.5âmol% for strain G20-9T. Strains G2-5T and G20-9T exhibited 98.2â% 16S rRNA gene sequence similarity, along with 82.3â% average nucleotide identity (ANI) and 25.0â% digital DNA-DNA hybridization (dDDH) values, indicating that they represent different species. Phylogenetic analyses based on both 16S rRNA gene and genome sequences revealed that strains G2-5T and G20-9T formed distinct phylogenic lineages within the genus Devosia. Strains G2-5T and G20-9T were most closely related to Devosia limi DSM 17137T and Devosia beringensis S02T with 97.7 and 96.9â% 16S rRNA gene sequence similarities, respectively. The ANI and dDDH values between strains G2-5T and G20-9T and other Devosia species were lower than 73.9 and 19.2â%, respectively, suggesting that they constitute novel species within the genus Devosia. Based on their distinct phenotypic, chemotaxonomic, and molecular characteristics, strains G2-5T and G20-9T represent two novel species of the genus Devosia, for which the names Devosia rhodophyticola sp. nov. (G2-5T=KACC 22601T=JCM 35404T) and Devosia algicola sp. nov. (G20-9T=KACC 22650T=JCM 35405T) are proposed, respectively.
