Anaerocolumna chitinilytica sp. nov., a chitin-decomposing anaerobic bacterium isolated from anoxic soil subjected to biological soil disinfestation

Abstract

An obligately anaerobic bacterial strain (CTTWT) belonging to the family Lachnospiraceae within the class Clostridia was isolated from an anoxic soil sample subjected to biological or reductive soil disinfestation. Cells of the strain were Gram-stain-positive, short rods with peritrichous flagella. The strain was saccharolytic and decomposed polysaccharides, chitin, xylan and β-1,3-glucan. Strain CTTWT decomposed cell biomass and cell-wall preparations of an ascomycete plant pathogen, Fusarium oxysporum f. sp. spinaciae. The strain produced acetate, ethanol, H2 and CO2 as fermentation products from the utilized substrates. The major cellular fatty acids of the strain were C16 : 1 ω7c dimethylacetal (DMA), C16 : 0 DMA and C18 : 1 ω7c DMA. The closely related species of strain CTTWT based on the 16S rRNA gene sequences were species in the genus Anaerocolumna with sequence similarities of 95.2–97.6 %. Results of genome analyses of strain CTTWT indicated that the genome size of the strain was 5.62 Mb and the genomic DNA G+C content was 38.3 mol%. Six 16S rRNA genes with five different sequences from each other were found in the genome. Strain CTTWT had genes encoding chitinase, xylanase, cellulase, β-glucosidase and nitrogenase as characteristic genes in the genome. Homologous genes encoding these proteins were found in the genomes of the related Anaerocolumna species, but the genomic and phenotypic properties of strain CTTWT were distinct from them. Based on the phylogenetic, genomic and phenotypic analyses, the name Anaerocolumna chitinilytica sp. nov., in the family Lachnospiraceae is proposed for strain CTTWT (=NBRC 112102T=DSM 110036T).