Oecophyllibacter saccharovorans gen. nov. sp. nov., a bacterial symbiont of the weaver ant Oecophylla smaragdina with a plasmid-borne sole rrn operon

In this study, acetic acid bacteria (AAB) strains Ha5T, Ta1 and Jb2 that constitute the core microbiota of weaver ant Oecophylla smaragdina were isolated from multiple ant colonies and were distinguished as different strains by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry and distinctive random-amplified polymorphic DNA (RAPD) fingerprints. These strains showed similar phenotypic characteristics and were considered a single species by multiple delineation indexes. 16S rRNA gene sequence-based phylogenetic analysis and phylogenomic analysis based on 96 core genes placed the strains in a distinct lineage in family Acetobacteraceae. Compared to Acetobacteraceae type members, these strains demonstrate average nucleotide identity (ANI), in-silico DNA-DNA hybridization (DDH) and average amino acid identity (AAI) values lower than proposed species-level cut-off values which indicated that they represent a novel genus of the family. Currently, strains Ha5T, Ta1 and Jb2 possess the smallest genomes (1.92-1.95 Mb) with significantly lower gene and protein numbers among family Acetobacteraceae. Intriguingly, the sole rrn operon in their genomes is plasmid-borne instead of chromosomally located. Furthermore, these strains harbour biosynthetic genes for various amino acids, cofactors and vitamins which supported a nutritional symbiotic interaction with the host O. smaragdina. Various phenotypic differences also distinguished the strains from closest relative genera in family Acetobacteraceae. Based on these results, these strains represent a novel species of a novel genus of family Acetobacteraceae, for which we propose the name Oecophyllibacter saccharovorans gen. nov. sp. nov., and strain Ha5T as the type strain.