Description of Azoarcus nasutitermitis sp. nov. and Azoarcus rhizosphaerae sp. nov., two nitrogen-fixing species isolated from termite nest and rhizosphere of Ficus religiosa.

A polyphasic taxonomic approach was used to characterise two presumably novel bacteria, designated strains CC-YHH838 and CC-YHH848 isolated from termite nest and rhizosphere of Ficus religiosa, respectively. These two nitrogen-fixing strains were observed to be Gram-staining-negative, aerobic rod, and colonies were yellowish in color. Growth of strains was observed at 20-37 °C, pH 7-8, and in the presence of 1-2% NaCl. Phylogenetic analyses based on 16S rRNA genes revealed a distinct taxonomic position attained by strain CC-YHH838 and CC-YHH848 associated with Thauera hydrothermalis (97.1% sequence identity), and formed a separate branch with Azoarcus indigens (95.4%), Aromatoleum aromaticum (96.2%), and lower sequence similarity to other species. The calculation of OrthoANI values pointed out strains CC-YHH838 and CC-YHH848 gave 78.9% and 79.8% compared to Thauera hydrothermalis, respectively. The major fatty acids (> 5%) were C, C cyclo, C 3-OH, Cω7c/Cω6c and Cω7c/Cω6c. The polar lipid profile comprised phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and unidentified aminophospholipid and phospholipids; the predominant polyamines were putrescine and spermidine. The predominant respiratory system was ubiquinone (Q-8) and the DNA G + C contents were 61.4 ± 0.1 mol% and 60.2 ± 1.3 mol%, respectively. Based on the phylogenetic and polyphasic comparisons, strains CC-YHH838 and CC-YHH848 are proposed to represent two novel species within the genus Azoarcus in the family Rhodocyclaceae, for which the name Azoarcus nasutitermitis sp. nov. (type strain CC-YHH838 = BCRC 81059 = JCM 32001) and Azoarcus rhizosphaerae sp. nov. (type strain CC-YHH848 = BCRC 81060 = JCM 32002) were proposed.