AUTHOR=Li Qian , Zhu Jianyu , Li Shoupeng , Zhang Ruiyong , Xiao Tangfu , Sand Wolfgang 

TITLE=Interactions Between Cells of Sulfobacillus thermosulfidooxidans and Leptospirillum ferriphilum During Pyrite Bioleaching

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.00044

DOI=10.3389/fmicb.2020.00044

ISSN=1664-302X

ABSTRACT=<p><italic>Sulfobacillus</italic> and <italic>Leptospirillum</italic> occur frequently in leaching systems. Here we investigated the effects of cells of <italic>L. ferriphilum</italic> on biofilm formation and leaching performance by <italic>S. thermosulfidooxidans</italic>. The effects were caused by the presence of <italic>L. ferriphilum</italic> or an addition of pyrite leach liquor from <italic>L. ferriphilum</italic>. Data show that the number of attached <italic>S. thermosulfidooxidans</italic> on pyrite increases, if the pyrite had been pre-colonized by living biofilms of <italic>L. ferriphilum</italic>, while it decreases if the pre-colonized biofilms had been inactivated. Coaggregation between <italic>S. thermosulfidooxidans</italic> and <italic>L. ferriphilum</italic> occurs during the dual-species biofilm formation, but different effects on bioleaching were noted, if the preculture of <italic>L. ferriphilum</italic> had been different. If <italic>L. ferriphilum</italic> had been pre-colonized on a pyrite, significantly negative effect was shown. However, if the two species were simultaneously inoculated into a sterile leaching system, the bioleaching efficiency was better than that of a pure culture of <italic>S. thermosulfidooxidans</italic>. The effect might be related to a metabolic preference of <italic>S. thermosulfidooxidans</italic>. If <italic>S. thermosulfidooxidans</italic> performed leaching in a filtered pyrite leachate from <italic>L. ferriphilum</italic>, the cells preferred to oxidize RISCs instead of ferrous ion and the number of attached cells decreased compared with the control. This study gives an indication that in a short-term multi-species leaching system the role of <italic>S. thermosufidooxidans</italic> may be related to the time of its introduction.</p>