Acidithiobacillus acidisediminis sp. nov., an acidophilic sulphur-oxidizing chemolithotroph isolated from acid mine drainage sediment.

Strain S30A2 ^T , isolated from the acid mine drainage sediment of Mengzi Copper Mine, Yunnan, is proposed to represent a novel species of the sulphur-oxidizing genus Acidithiobacillus . Cells were Gram-stain-negative, non-endospore forming, highly motile with one or two monopolar flagella and rod-shaped. The strain was mesophilic, growing at 30-50 °C (optimum, 38 °C), acidophilic, growing at pH 2.0-4.5 (optimum, pH 2.5), and tolerant of 0-4 % (w/v; 684 mol l ^-1 ) NaCl. The 16S rRNA gene-based sequence analysis showed that strain S30A2 ^T belongs to the genus Acidithiobacillus and shows the largest similarity of 96.6 % to the type strain Acidithiobacillus caldus KU ^T . The genomic DNA G+C content of strain S30A2 ^T was 59.25 mol%. The average nucleotide identity ANIb and ANIm values between strain S30A2 ^T and A. caldus KU ^T were 70.95 and 89.78 %, respectively and the digital DNA-DNA hybridization value was 24.9 %. Strain S30A2 ^T was strictly aerobic and could utilize elementary sulphur and tetrathionate to support chemolithotrophic growth. The major cellular fatty acid of S30A2 ^T was C _19 : 1 ω7 c . The respiratory quinones were ubiquinone-8 and ubiquinone-7. Based upon its phylogenetic, genetic, phenotypic, physiologic and chemotaxonomic characteristics, strain S30A2 ^T is considered to represent a novel species of the genus Acidithiobacillus , for which the name Acidithiobacillus acidisediminis sp. nov. is proposed. The type strain is S30A2 ^T (=CGMCC 1.17059 ^T =KCTC 72580 ^T ).