A novel endophytic bacterium, designated strain HZ7T, was isolated from the root nodules of Robinia pseudoacacia growing in a lead-zinc mine in Mianxian County, Shaanxi Province, China. Cells were Gram-reaction-negative, aerobic, motile, rod-shaped, methyl-red-negative, catalase-positive, positive for chitosan-degrading activity and did not produce H2S. Strain HZ7T grew at 4-45 °C (optimum 25-30 °C), at pH 5-9 (optimum pH 7-8) and with 0-1 % (w/v) NaCl. The quinone type was ubiquinone 8 (UQ-8). The major fatty acids were identified as C16 : 0, C17 : 0 cyclo and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c). The G+C content of the genomic DNA was 68.5 mol% by whole genome sequencing. According to 16S rRNA gene sequence analysis, the closest phylogenetic relative was Mitsuaria chitosanitabida 3001T (99.05 % similarity). Genome relatedness was computed using average nucleotide identity and genome-to-genome distance analysis, both of which strongly supported strain HZ7Tas belonging to the genus Mitsuaria as a representative of a novel species. On the basis of phylogenetic analysis, chemotaxonomic data and physiological characteristics, strain HZ7T represents a novel species of the genus Mitsuaria, for which the name Mitsuaria noduli sp. nov. is proposed. The type strain is HZ7T (=JCM 31671T=CCTCC AB 2014353T).
Keywords: 16S rRNA gene sequence; Mitsuaria noduli; polyphasic taxonomy.