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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 T . 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 18:1 ω7c, C 16:0 , and summed in feature 3. The composition of polar lipids in the strain AK27 T included phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, one unidentified amino lipid, two unidentified aminophospholipids, two unidentified phospholipids, and six unidentified lipids. The genomic DNA of strain AK27 T exhibited a G+C content of 56.4 mol%. Based on the analysis of 16S rRNA gene sequence, strain AK27 T showed sequence similarity to M. ramblicola D7 T and M. zhoushanense WM3 T as 98.99% and 98.58%, respectively. Compared to other type strains of the Marinobacterium genus, strain AK27 T exhibited sequence similarities ranging from 91.7% to 96.4%. When compared to Marinobacterium zhoushanense WM3 T and Marinobacterium ramblicola D7 T , strain AK27 T 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 T 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 T as a novel species within the genus Marinobacterium. The proposed name for this novel species is Marinobacterium lacunae sp. nov., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Marine microbes produce polysaccharides with unique physicochemical and functional properties that help them survive in harsh marine environments. However, only a handful of marine exopolysaccharides (EPSs) have been reported to date. The present study explored the seashore of Visakhapatnam, India, to report a novel exopolysaccharide designated as Br42 produced by Brevibacillus borstelensis M42. The isolate was identified through morphological, biochemical, phylogenetic, and genome sequencing analysis. The studies on fermentation kinetics revealed that EPS Br42 was a primary metabolite with a maximum production of 1.88 ± 0.02 g/L after 60 h when production broth was fortified with 2% glucose. Additionally, EPS Br42 was found to be a heteropolysaccharide consisting of glucose and galacturonic acid with a molecular weight of about 286 kDa. Interestingly, this molecule possesses industrially relevant functional properties such as water-holding (510 ± 0.35%), oil-holding (374 ± 0.12% for coconut oil and 384 ± 0.35% for olive oil), and swelling capacities (146.6 ± 5.75%). EPS Br42 could form an emulsion that was stable at a wide pH range for about 72 h and, in fact, performed better as compared to Span 20, a commercially used synthetic emulsifier. Moreover, this EPS was also found to be heat stable and exhibited non-Newtonian pseudoplastic behavior. These physicochemical and functional properties of polysaccharides suggest that the EPS Br42 has potential for multifarious industrial applications as an emulsifier, stabilizer, viscosifier, and binding agent., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)