National Institute Of Oceanography( NIO ) - Two new bacteria isolated from the deep-sea sediment sample

Two new bacteria isolated from the deep-sea sediment sample

Scientists of CCMB, Hyderabad in collaboration with NIO, Goa have isolated culturable bacteria from deep-sea sediments collected from the Chagos Trench in the Indian Ocean below the water depth of 5904 m. Bacteria were isolated from 50-70 cm section of a 4.6 m long sediment core. These sediments were approximately 50,000 years old. Two strains of bacteria belonging to a new species Brevibacterium oceani were described from these sediments using 16S rRNA sequencing. The almost-complete 16S rRNA gene sequences of these two strains showed 99.9% similarity among themselves. Following BLAST analysis, the two strains showed 97.9 to 98.4 % similarity to other Brevibacterium species (see Fig.). DNA-DNA dot-blot hybridization of these two strains with other known Brevibacterium species showed relatedness of only 35-41%. A DNA-DNA relatedness of 70% is used as the cut-off point for species delineation. Based on these results and differences in other phenotypic characteristics, these two strains belong to a novel species and the new species name Brevibacterium oceani was proposed. (Int. J. Systemat. Evolut. Microbiol.: 58(1); 2008; 57-60) From the same sediments, two more new strains belonging to a new species Microbacterium indicum were described. Biochemical characteristics, fatty acid profile, polar lipid contents and levels of DNA-DNA hybridization techniques were used to report this new species. 16S rRNA gene sequence similarity between the two strains was 99.7% and with other species of Microbacterium it varied from 97.2 to 97.4 %. However the two new strains exhibited 32-34% DNA-DNA relatedness to other species of Microbacterium. Therefore, based on differences observed in the phenotypic and chemotaxonomic characters, these two strains belong to a novel species of Microbacterium to which the name Microbacterium indicum was proposed. (Int. J. Systemat. Evolut. Microbiol. : 57(8); 2007; 1819-1822). These results indicate that deep-sea sediments hold a hidden wealth of microbial diversity which remains to be explored.

Neighbour-joining phylogenetic tree based on 16S rRNA gene sequences showing the position of new bacteria and closely related species of the genus Brevibacterium. Accession number given in parentheses

To consult original article, refer :
Bhadra, B.; Raghukumar, C.; Pindi, P.K.; Shivaji, S. Brevibacterium oceanic sp. nov., isolated from deep-sea sediment of the Chagos Trench, Indian Ocean. Int. J. Systemat. Evolut. Microbiol.: 58(1); 2008; 57-60.

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