Members of the class Blastocatellia are frequently found in soils with a neutral and (slightly) basic pH where they constitute an important fraction of the microbial community. A novel representative of the class Blastocatellia was isolated from a Ghanaian soil and was characterized in detail. Cells of strain A24_SHP_-5_238T were non-motile rods that divided by binary fission and formed orange to salmon-coloured colonies on agar plates. Strain A24_SHP_-5_238T tolerated pH values of pH 6.0-9.0 (best growth at pH 7.0-8.5) and temperature values of 8-45 °C (best growth at 33-40 °C). It grew chemo-organoheterotrophically on several sugars, a few amino acids, organic acids and different complex protein substrates. In addition, strain A24_SHP_-5_238T was able to use nitrate as an alternative electron acceptor in the absence of oxygen. Major fatty acids of A24_SHP_-5_238T were iso-C15 : 0, summed feature 1 (C13 : 0 3-OH/iso-C15 : 1 H), summed feature 3 (C16 : 1ω7c/C16 : 1ω6c), anteiso-C17 : 0 and anteiso-C15 : 0. The major quinone was MK-8, and the DNA G+C content was 53.5 mol%. The closest described phylogenetic relatives were Aridibacter famidurans A22_HD_4HT and Aridibacter kavangonensis Ac_23_E3T with a 16S rRNA gene sequence identity of 97.6 and 97.2 %, respectively. The DNA-DNA hybridization values (<28.5 %) confirmed that A24_SHP_-5_238T represents a novel species within the genus Aridibacter. Based on its morphological, physiological and molecular characteristics, we propose the novel species Aridibacter nitratireducens sp. nov. (type strain A24_SHP_-5_238T = DSM 102177T = CECT 9235T).
Keywords: Acidobacteria; Blastocatellaceae; preferred growth on complex nitrogen compounds; soil environment.