A psychrotolerant Caulobacter sp. from Russian polar tundra soil

Abstract  train Z-0024, a psychrotolerant aerobic heterotrophic representative of the prosthecate bacteria of the genus Caulobacter, was isolated from a methanotrophic enrichment obtained from Russian polar tundra soil. The cells of the new isolate are vibrios (0.5–0.6 × 1.3–1.8 mm) with a polar stalk. The organism grows in a temperature range from 5 to 36°C, with an optimum at 20°C. The pH range for growth is from 4.5 to 7.0 with an optimum at pH 6.0. Strain Z-0024 utilizes a wide range of organic compounds: sugars, amino acids, volatile fatty acids, and primary alcohols. It tolerates a NaCl concentration in the medium of up to 15 g/l. The G+C content of DNA is 66.6 mol %. The 16S rRNA gene sequence analysis revealed that strain Z-0024 belongs to the cluster of Caulobacter species, showing a 98.8–99.2% sequence similarity to them. DNA-DNA hybridization revealed a low level of homology (24%) between strain Z-0024 and C. vibrioides ATCC 15252. The new isolate is described as Caulobacter sp. Z-0024.