Lysobacter ruishenii sp. nov., a chlorothalonil-degrading bacterium isolated from a long-term chlorothalonil-contaminated soil

Abstract

An aerobic, Gram-negative bacterial strain, designated CTN-1T, capable of degrading chlorothalonil was isolated from a long-term chlorothalonil-contaminated soil in China, and was subjected to a polyphasic taxonomic investigation. Strain CTN-1T grew at 15–37 °C (optimum 28–30 °C) and at pH 6.0–9.0 (optimum pH 7.0–7.5). The G+C content of the total DNA was 67.1 mol%. Based on 16S rRNA gene sequence analysis, strain CTN-1T was related most closely to Lysobacter daejeonensis DSM 17634T (97.1 % similarity), L. soli DCY21T (95.7 %), L. concretionis Ko07T (95.5 %), L. gummosus LMG 8763T (95.3 %) and L. niastensis DSM 18481T (95.2 %). The novel strain showed less than 95.0 % 16S rRNA gene sequence similarity to the type strains of other Lysobacter species. The major cellular fatty acids of strain CNT-1T were iso-C16 : 0 (23.0 %), iso-C15 : 0 (21.4 %) and iso-C17 : 1 ω9c (15.3 %). The major isoprenoid quinone was Q-8 (99 %), and the major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. These chemotaxonomic data supported the affiliation of strain CTN-1T to the genus Lysobacter. Levels of DNA–DNA relatedness between strain CTN-1T and L. daejeonensis DSM 17634T were 34.6–36.1 %. Phylogenetic analysis based on 16S rRNA gene sequences, DNA–DNA hybridization data and biochemical and physiological characteristics strongly supported the genotypic and phenotypic differentiation of strain CTN-1T from recognized species of the genus Lysobacter. Strain CTN-1T is therefore considered to represent a novel species of the genus Lysobacter, for which the name Lysobacter ruishenii sp. nov. is proposed. The type strain is CTN-1T (=DSM 22393T =CGMCC 1.10136T).