Citrobacter arsenatis sp. nov., an arsenate-reducing bacterium isolated from freshwater sediment.

A novel arsenate-reducing bacterium, LY-1 ^T , was isolated from freshwater sediment in Huangshi, China. Morphological analysis indicated that the cells were shaped like rods and were gram-negative. The major fatty acids (> 10%) were C _16:0 , summed feature 3 (C _16:1 ω7c, C _16:1 ω6c) and summed feature 8 (C _18:1 ω7c, C _18:1 ω6c). An assessment of the phylogeny based on 16S rRNA gene sequences indicated that the strain LY-1 ^T belonged to the genus Citrobacter, while further analysis based on the recN gene indicated that LY-1 ^T occupies a distinct phylogenetic niche within the Citrobacter genus. Moreover, average nucleotide identity and digital DNA-DNA hybridization between the strain LY-1 ^T and the type strains of closely related species of the genus Citrobacter (C. europaeus, C. brakii, C. portucalensis, C. freundii, C. werkmanii, C. cronae, C. youngae, C. pasteurii, C. tructae, C. gillenii, and C. murliniae) were 85.8-93.8% and 31.2-56.9%, respectively. In addition, the LY-1 ^T strain's capacity to metabolize various compounds and its characteristic G + C content of 51.9% were also distinct from other species of the Citrobacter genus. These discriminatory features cumulatively indicate the LY-1 ^T strain as a new species within the Citrobacter genus. We propose the species name Citrobacter arsenatis for this new species, with LY-1 ^T (= CCTCC AB 2019169 ^T  = KCTC 72440 ^T ) as the type strain.
(© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)