Culicoidibacter larvae gen. nov., sp. nov., from the gastrointestinal tract of the biting midge (Culicoides sonorensis) larva, belongs to a novel lineage Culicoidibacteraceae fam. nov., Culicoidibacterales ord. nov. and Culicoidibacteria classis nov. of the phylum Firmicutes

Abstract

Strain CS-1T, a novel facultative anaerobic bacterium, was isolated from the larval gastrointestinal tract of the biting midge, Culicoides sonorensis, a vector of the epizootic haemorrhagic disease virus and the bluetongue virus. Cells were Gram-stain-positive, non-motile, non-spore-forming, pleomorphic rods. Optimal growth occurred at pH 7.5 and 37 °C. The G+C content of the genomic DNA was 38.3 mol%, estimated by using HPLC. The dominant cellular fatty acids were C14 : 0 (45.9 %) and C16 : 0 (26.6 %). The polar lipid profile comprised glycolipids, diphosphatidylglycerol, phospholipids and phosphoglycolipids. Respiratory quinones were not detected. Strain CS-1T had very low 16S rRNA gene similarity to members of the phylum Firmicutes : Macrococcus canis KM45013T (85 % similarity) and Turicibacter sanguinis MOL361T (88 % similarity). Phylogenetic analysis based on 16S rRNA, rpoB, gyrB genes, and conserved protein sequences of the whole genome revealed that strain CS-1T was related to members of the classes Bacilli and Erysipelotrichia within the phylum Firmicutes . Furthermore, average nucleotide identity and digital DNA–DNA hybridization analyses of the whole genome revealed very low sequence similarity to species of Bacilli and Erysipelotrichaceae ( Macrococcus canis KM45013T and Turicibacter sp. H121). These results indicate that strain CS-1T belongs to the phylum Firmicutes and represents a new species of a novel genus, family, order and class. Based on the phenotypic, chemotaxonomic, phylogenetic and genomic characteristics, we propose the novel taxon Culicoidibacter larvae gen. nov., sp. nov. with the type strain CS-1T (=CCUG 71726T=DSM 106607T) within the hereby new proposed novel family Culicoidibacteraceae fam. nov., new order Culicoidibacaterales ord. nov. and new class Culicoidibacteria classis nov. in the phylum Firmicutes .