Entomobacter blattae gen. nov., sp. nov., a new member of the Acetobacteraceae isolated from the gut of the cockroach Gromphadorhina portentosa

A novel bacterium designated G55GP(T) and pertaining to the family Acetobacteraceae was isolated from the gut of the Madagascar hissing cockroach Gromphadorhina portentosa. The Gram-negative cells were rod-shaped and non-motile. The complete 16S rRNA sequence of the strain G55GP(T) showed the highest pairwise similarity to Gluconacetobacter johannae CFN-Cf-55(T) (95.35 %), suggesting it represents a potential new genus of the family Acetobacteraceae. Phylogenetic analysis based on 16S rRNA gene and 106 orthologous housekeeping protein sequences revealed that G55GPT forms a monophyletic clade with the genus Commensalibacter, which thus far has also been isolated exclusively from insects. The G55GP(T) genome size was 2.70 Mbp, and the G+C content was 45.4 mol%, which is lower than most acetic acid bacteria (51-68 mol%) but comparable to Swingsia samuiensis AH83(T) (45.1 mol%) and higher than Commensalibacter intestini A911(T) (36.8 mol%). Overall genome relatedness indices based on gene and protein sequences strongly supported the assignment of G55GP(T) to a new genus within the family Acetobacteraceae. The percentage of conserved proteins, which is a useful metric for genus differentiation, was below 54 % when comparing G55GP(T) to type strains of acetic acid bacteria, thus strongly supporting our hypothesis that G55GP(T) is a member of a yet-undescribed genus. The fatty acid composition of G55GP(T) differed from that of closely related acetic acid bacteria, particularly given the presence of C-19:1 omega 9c/omega 11c and the absence of C-14:0 and C-14:0 2-OH fatty acids. Strain G55GPT also differed in terms of metabolic features such as its ability to produce acid from d-mannitol, and its inability to produce acetic acid from ethanol or to oxidize glycerol to dihydroxyacetone. Based on the results of combined genomic, phenotypic and phylogenetic characterizations, isolate G55GP(T) (=LMG 31394(T)=DSM 111244(T)) is considered to represent a new species in a new genus, for which we propose the name Entomobacter blattae gen. nov., sp. nov.

Automated summary

A novel bacterium G55GP(T) isolated from the gut of Madagascar hissing cockroach belongs to the Acetobacteraceae family, possibly representing a new genus. Phylogenetic analysis suggests that G55GP(T) forms a monophyletic clade with Commensalibacter, a genus also isolated exclusively from insects.