Citrobacter enshiensis sp. nov., isolated from seleniferous soil

Two Gram-stain-negative, facultative anaerobic, rod-shaped bacterial strains, S171 T and S2-9, were isolated from seleniferous soil in China. Comprehensive phylogenetic analyses based on 16S rRNA genes, multilocus sequences and whole genome sequences indicated that the two strains belonged to the genus Citrobacter . The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values of strains S171 T and S2-9 with the closest relative Citrobacter koseri NCTC 10786 T were 83.6–83.7% and 27.7–27.8 %, respectively, which were below the species cutoff values. The ANI and dDDH values between the two strains were 97.9% and 84.8 %, respectively. The biochemical characteristics revealed that selenite tolerance, H 2 S and indole production, arginine dihydrolase, ornithine decarboxylase, as well as acid production from carbon sources such as d -sorbitol and arbutin are distinctive features of the two strains. Based on these results, strain S171 T and strain S2-9 represent a novel species of the genus Citrobacter , for which the name Citrobacter enshiensis sp. nov. is proposed, with strain S171 T (=GDMCC 1.3637 T =JCM 35851 T ) as the type strain. The genome size of strain S171 T was 4.92 Mb with a G+C content of 52.6 mol%. The genome size of strain S2-9 was 4.89 Mb with a G+C content of 52.6 mol%.