Diversity and Activity of Methanotrophic Related Bacteria in Subsurface Sediments of the Krishna-Godavari Basin, India

The present study assesses the distribution, diversity and activity of aerobic methanotrophic related bacteria (MRB) dwelling in Krishna-Godavari (KG) basin, India. The counts of MRB ranged from non-detectable (ND) to 8.6 × 10⁴ CFU gram dry weight of the sediment, with maximum counts at 24.2 m below seafloor. Greater methanotrophic bacterial abundance was at the surface/subsurface sediments of the core at station MD161-8 than at the bottom sediments. Identification of these isolates by 16S rDNA sequence analysis showed their taxonomic affiliation to Alcanivorax, Methylophaga, Marinobacter, Joostella, Methylobacterium, Desulfovibrio species and other uncultured bacterial clones. The isolates grew under optimum pH of 8, temperature of 28°C and salinity of 35, and on different carbon sources like yeast extract, D-glucose, ethanol and methanol. The addition of nitrogen sources like amino acids and yeast extract improved methanotrophic activity by the isolates. These results add to our understanding of MRB and their activity in modulating the emission of methane from gas hydraterich ecosystems like the KG basin.