The characterization of the novel bacterial strains isolated from the surface sediment in the Ulleung Basin, East Sea, Korea

Abstract

Three novel bacteria designated UBM1-P, UBM1-4 and UBM1-5, were isolated from a deep sea sediment sample from the Ulleung Basin, East Sea, Korea. Strain UBM1-P was aerobic, gram positive short straight rods with spore distended vegetative cells which grew optimally at 35℃, 7.5pH and 0.5% NaCl concentration. Strain UBM1-P has 99% 16S rRNA gene sequence with its closest relative, Bacillus vietnamensis but they differ extremely in their physiological and chemotaxonomical characteristics, enough to rule it out as a subspecies. The two remaining strains are gram positive, spore forming, mesophilic and anaerobic rod shaped bacteria with different physiological properties. Strain UBM1-4 grew optimally at 15-20℃, 7.0 H and 5.0% NaCl concentration; can grow using yeast extract or ketogluconate as its sole energy source while being able to survive anaerobically using nitrates as an electron acceptor. Strain UBM1-5 grew optimally at 15-20℃, 7.5 pH and 0.5% NaCl concentration, used saccharose or ketogluconate as sole energy source and was able to grow anaerobically respiring with nitrates, thiosulphate and fumarate as electron acceptors. The 16S rRNA gene sequences of the novel strains showed similarities to their closest relatives within the range of 92% to 95% except for the only aerobic strain which showed 99% similarity but maintains its novelty due to other differentiating factors such as its chemotaxonomic characteristics. The three strains are proposed to be described as novel species on the basis of their 16S rDNA comparison, phenotypic, chemotaxonomic and biochemical characteristics.