Marinomonas agarivorans sp. nov., an agar-degrading marine bacterium isolated from red algae.

A Gram-stain-negative, aerobic and curved-rod-shaped bacterium, designated QM202T, was isolated from red algae (Gracilaria blodgettii). Cells of strain QM202T were 0.2-0.3 µm wide and 1.0-2.5 µm long, catalase-negative and oxidase-positive. The strain exhibited an agar-degrading activity. It was motile by means of a single polar flagellum. Optimal growth occurred at 28-30 °C, pH 7.0-7.5 and in the presence of 2.0-3.0 % (w/v) NaCl. The DNA G+C content was 41.4 mol%. The isoprenoid quinone was identified as Q-8. Phophatidylethanolamine and phosphatidylglycerol were the predominant phospholipids. The dominant fatty acids were C18:1ω7c, C16:0 and C16:1ω7c and/or iso-C15:0 2-OH. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain QM202T belonged to the genus Marinomonas. The closest described neighbour in terms of 16S rRNA gene sequence identity was Marinomonas blandensis MED121T (95.5 %). The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness indicated that strain QM202T can be considered to represent a novel species, Marinomonas agarivorans sp. nov. The type strain is QM202T (=KCTC 52475T=MCCC 1H00145T).

Agaribacter flavus sp. nov., isolated from red algae.

A Gram-stain-negative, non-motile, aerobic, curved-rod bacterium, designated as strain 2p52T, was isolated from the marine algae Gracilaria blodgettii collected off the coast of Lingshui county, in Hainan province, China. Strain 2p52T grew at 15-42 °C (optimally at 30-33 °C), at pH 6.0-10.0 (7.5-8.0) and in the presence of 1.0-8.0 % (w/v) NaCl (2.0-3.0 %). The most closely related species was Agaribacter marinus (96.5 % 16S rRNA gene sequence similarity). Phylogenetic analysis based on the sequence of the 16S rRNA gene revealed that strain 2p52T belonged to the genus Agaribacter. The novel strain contained phophatidylethanolamine and phosphatidylglycerol as the major polar lipids. The predominant isoprenoid quinine was Q-8, and the DNA G+C content was 43.2 mol%. The major cellular fatty acids were C16 : 1ω7c and/or iso-C15 : 0 2-OH, C16 : 0, and C18 : 1ω7c. The phenotypic and systematic comparative analyses indicated that the isolate is representative of a novel species of the genus Agaribacter, and the name Agaribacter flavus sp. nov. is proposed. The type strain is 2p52T (=KCTC 52473T=MCCC 1H00151T).

Marinobacter salexigens sp. nov., isolated from marine sediment.

A novel bacterium, designated as strain HJR7T, was isolated from a marine sediment sample collected from the coastal area of Weihai, China (121° 57' E, 37° 29' N). Cells were Gram-stain-negative, facultative anaerobic, non-motile and rod-shaped. The temperature, pH and NaCl ranges for growth were determined as 4-40 °C, pH 6.5-9.5 and 0.5-15.0 % (w/v), respectively. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain HJR7T belongs to the genus Marinobacter in the family Alteromonadaceae. The most closely related species were Marinobacter aromaticivorans (97.6 % 16S rRNA gene sequence similarity) and Marinobacter maritimus (97.3 % similarity). Ubiquinone 9 (Q-9) was the only respiratory quinone detected in strain HJR7T. The major fatty acids of strain HJR7T were C12 : 0, C16 : 0, C16 : 0 N alcohol, C18 : 1ω9c and C18 : 3ω6, 9, 12c. The major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, and an unidentified phospholipid. The DNA G+C content of strain HJR7T was 53.7 mol%. On the basis of phylogenetic, genotypic, phenotypic, and chemotaxonomic analyses, strain HJR7T represents a novel species within the genus Marinobacter, for which the name Marinobacter salexigens sp. nov. is proposed. The type strain is HJR7T (=KCTC 52545T=MCCC 1H00176T).