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-1(T), 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-1(T) 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-1(T) was related most closely to Lysobacter daejeonensis DSM 17634(T) (97.1 % similarity), L. soli DCY21(T) (95.7 %), L. concretionis Ko07(T) (95.5 %), L. gummosus LMG 8763(T) (95.3 %) and L. niastensis DSM 18481(T) (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-1(T) were iso-C₁₆:₀ (23.0 %), iso-C₁₅:₀ (21.4 %) and iso-C₁₇:₁ω9c (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-1(T) to the genus Lysobacter. Levels of DNA-DNA relatedness between strain CTN-1(T) and L. daejeonensis DSM 17634(T) 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-1(T) from recognized species of the genus Lysobacter. Strain CTN-1(T) 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-1(T) (=DSM 22393(T) =CGMCC 1.10136(T)).