Clostridium Fungisolvens Sp. Nov., A New Beta-1,3-Glucan-Decomposing Bacterium Isolated From Anoxic Soil Subjected To Biological Soil Disinfestation

Biological soil disinfestation (BSD) or reductive soil disinfestation (RSD) is a bioremediation method used to suppress or eliminate soil-borne plant pathogens by stimulating activities of indigenous anaerobic bacteria of the soil. An anaerobic bacterial strain (TW1(T)) was isolated from an anoxic soil sample subjected to the BSD treatment and comprehensively characterized. Cells of the strain were Gram-stain-positive, slightly curved and motile rods producing terminal spores. The strain was aero-tolerant. Strain TW1(T) was saccharolytic and produced acetate, butyrate, H-2 and CO2 as fermentation end products. Strain TW1(T) decomposed beta-1,3-glucan (curdlan and laminarin) and degraded mycelial cells of an ascomycete Fusarium plant pathogen. Major cellular fatty acids of strain TW1(T) were C-14:0, C-14:0 dimethylacetal (DMA), C-16:0 aldehyde and C-16:0 DMA. Strain TW1(T) made a group on the phylogenetic tree constructed based on 16S rRNA gene sequences with species such as Clostridium fallax (96.3%) and Clostridium polyendosporum (96.0%). Whole genome analysis of strain TW1(T) showed that the total length of the genome was 5.28 Mb with the DNA G+C content of 31.3 mol%. The average nucleotide identity (ANIb) between strain TW1(T) and C. fallax was 71.2 %. Presence of the genes encoding laminarinase or GH16 beta-glucosidase was confirmed from the genome analysis of strain TW1(T). Based on the genomic, phylogenetic and phenotypic properties obtained, we propose strain TW1(T) should be assigned in the genus Clostridium in the family Clostridiaceae as Clostridium fungisolvens sp. nov. The type strain TW1(T) (=NBRC 112097(T)=DSM 110791(T)).