Limnobacter olei sp. nov., a Novel Diesel-Degrading Bacterium Isolated from Oil-Contaminated Soil

A bacterial strain P1^T, capable of degrading diesel and converting thiosulfate to sulfate was isolated from an oil-contaminated soil sample. The cells were Gram-stain-negative, slightly curved rods and motile with a single polar flagellum. Growth of the strain was observed at 4-45 °C (optimum at 28 °C), at pH 4.0-12.0 (optimum at pH 10.0) and with 0-15.0% (w/v) NaCl (optimum at 2.0%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain P1^T was closely related to the members of the genus Limnobacter, with the highest sequence similarity to Limnobacter thiooxidans DSM 13612 ^T (99.8%), followed by Limnobacter alexandrii LZ-4 ^T (99.4%), Limnobacter parvus YS8-69 ^T (98.8%), Limnobacter litoralis KP1-19 ^T (97.6%), and Limnobacter humi UCM-39 ^T (97.5%). The draft genome sequence of strain P1^T was 3.40 Mb long, with a DNA G + C content of 52.4%. The average nucleotide identity and digital DNA-DNA hybridization values between strain P1^T and the closely related type strains were in the range of 71.8-85.1% and 18.1-28.7%, respectively. The predominant cellular fatty acids of strain P1^T included C_{16: 0}, summed feature 3 (C_{16: 1} ɷ7c and/or C_{16: 1} ɷ6c), summed feature 8 (C_{18: 1} ɷ7c and/or C_{18: 1} ɷ6c), and summed feature 7 (C_{19: 1} ɷ6c and/or C_{19: 1} ɷ7c and/or C_{19: 1} cyclo). In addition, the main polar lipid was composed of diphosphatidylglycerol, phosphatidylethanolamine, and phosphatidylglycerol. Q-8 was the sole respiratory quinone. Based on the polyphasic characterization, strain P1^T (= KCTC 72814 ^T = CCTCC AB 2019403 ^T) represents a novel species of the genus Limnobacter, for which the name Limnobacter olei sp. nov. is proposed.