Marinobacterium lacunae sp. nov. isolated from estuarine sediment.

A novel motile bacterium was isolated from a sediment sample collected in Kochi backwaters, Kerala, India. This bacterium is Gram negative, rod shaped, 1.0-1.5 µm wide, and 2.0-3.0 µm long. It was designated as strain AK27. Colonies were grown on marine agar displayed circular, off-white, shiny, moist, translucent, flat, margin entire, 1-2 mm in diameter. The major fatty acids identified in this strain were C ω7c, C, and summed in feature 3. The composition of polar lipids in the strain AK27 included phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, one unidentified amino lipid, two unidentified aminophospholipids, two unidentified phospholipids, and six unidentified lipids. The genomic DNA of strain AK27 exhibited a G+C content of 56.4 mol%. Based on the analysis of 16S rRNA gene sequence, strain AK27 showed sequence similarity to M. ramblicola D7 and M. zhoushanense WM3 as 98.99% and 98.58%, respectively. Compared to other type strains of the Marinobacterium genus, strain AK27 exhibited sequence similarities ranging from 91.7% to 96.4%. When compared to Marinobacterium zhoushanense WM3 and Marinobacterium ramblicola D7, strain AK27 exhibited average nucleotide identity values of 80.25% and 79.97%, and dDDH values of 22.9% and 22.6%, respectively. The genome size of the strain AK27 was 4.55 Mb, with 4,229 coding sequences. Based on the observed phenotypic and chemotaxonomic features, and the results of phylogenetic and phylogenomic analysis, this study proposes the classification of strain AK27 as a novel species within the genus Marinobacterium. The proposed name for this novel species is Marinobacterium lacunae sp. nov.