Some physiological properties of three novel Fe(II)- and sulfur-oxidizing strains affiliated to Alicyclobacillus

This study focused on the soils of sofataric region and acid mine drainage from a copper mine. Based on cultivation, 8 and 6 strains that grow on Fe(H) and sulfur compounds, respectively, were obtained from samples from these two environments. Analysis of 16S rRNA genes of the 14 strains indicated that they were affiliated to Acidithiobacillus, Alicyclobacillus, Sulfobacillus and Leptospirillum. Physiological and phylogenetic studies indicated that three strains (TC-34, TC-71 and ZJ-6) might represent three novel members of Alicyclobacillus. These strains showed 94.8-97.1% 16S rRNA gene identity to other species of Aliclyclobacillus. Otherwise, strain TC-34, TC-71 and ZJ-6 showed a range of phenotypic characteristics that differentiated them from previously recognized Alicyclobacillus species, including the growth temperature, assimilation of carbon sources and production of acids from a range of compounds. Chemoautotrophic growth using Fe2+, elemental sulfur and tetrathionate as sole energy source was observed. Especially strain TC-71 was obligately dependent on Fe(II) for growth and quickly oxidized Fe2+. It is concluded that the Fe(II)-oxidizers are metabolically diverse and represent novel Alicyclobacillus species. These are proposed to take part in biogeochemical cycling of iron and Sulfur in the solfataric region and could be relevant for biomining.