Lysobacter oligotrophicus sp. nov., isolated from an Antarctic freshwater lake in Antarctica

Abstract

A Gram-stain-negative, non-spore-forming, rod-shaped, aerobic bacterium (strain 107-E2T) was isolated from freshwater samples containing microbial mats collected at a lake in Skarvsnes, Antarctica (temporary lake name, Lake Tanago Ike). Strain 107-E2T grew between 5 and 25 °C, with an optimum of 23 °C. Moreover, colony formation was observed on agar media even at −5 °C. The pH range for growth was between 6.0 and 9.0, with an optimum of pH 7.0–8.0. The range of NaCl concentration for growth was between 0.0 and 0.5 % (w/v), with an optimum of 0.0 %. No growth was observed in media containing organic compounds at high concentrations, which indicated that strain 107-E2T was an oligotroph. In the late stationary phase, strain 107-E2T produced a dark brown water-soluble pigment. Esterase, amylase and protease production was observed. Antimicrobial-lytic activities for Gram-negative bacteria and yeast were observed. Ubiquinone-8 was the major respiratory quinone. The major fatty acids were iso-C15 : 0, iso-C17 : 1ω9c and iso-C15 : 1 at 5. The G+C content of genomic DNA was 66.1 mol%. Analysis of the 16S rRNA gene sequences revealed that strain 107-E2T belonged to the genus Lysobacter , and low DNA–DNA relatedness values with closely related species distinguished strain 107-E2T from recognized species of the genus Lysobacter . The phylogenetic situation and physiological characteristics indicated that strain 107-E2T should be classified as a representative of a novel species of the genus Lysobacter , for which the name Lysobacter oligotrophicus sp. nov. is proposed. The type strain is 107-E2T ( = JCM 18257T = ATCC BAA-2438T).