gen. nov., sp. nov., an ammonia-tolerant formate-utilizing bacterium originating from a biogas process.

A strictly anaerobic bacterial strain, designated as AMB_02, was isolated from a propionate enrichment culture obtained from a high-ammonia biogas digester. The cells were anaerobic and coccoid (0.5 µm), often appearing as diplococci or in a short chain of three to four cells. Growth was observed between 20 and 45 °C (optimum at 37-39 °C), with an initial pH of 6.5-9.0 (optimum pH 8.0-8.5), and the species tolerated up to 0.8 M NHCl and 0.5 M NaCl. The major cellular fatty acids were C (31.6%), C (14.6%) and C (13.3%). AMB_02 grew with formate, carbohydrates and aa, including asparagine, histidine, tryptone and tryptophan. Acetate was the major product formed. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain AMB_02 was most closely related to the species (92.5%). The genome of strain AMB_02 was 2.5 Mb in length with a G+C content of 34.8 mol%, and 2,354 protein-coding genes were predicted. Furthermore, genes coding for the reductive glycine pathway potentially used for formate metabolism were identified. Comparative genomic analysis of AMB_02 revealed the closest similarity to [21.2% digital DNA-DNA hybridization (dDDH) and 77.4% average nt identity (ANI)] and to (4.4% dDDH and 76.9% ANI). Based on the phenotypic characteristics and phylogenetic analyses, AMB_02 is regarded as a novel genus, , within the family for which the species name is proposed. The type strain is AMB_02=DSM 110248=JCM 39108.