Community structure and dynamics of moderately thermophilic microorganisms during bioleaching of low-grade chalcopyrite by column reactor

Abstract:

In this study, a mixed culture of moderately thermophilic microorganisms was enriched from several acid mine drainage samples collected from copper mines in China at 45 °C. The pH and copper concentration in the leachate were monitored during bioleaching low-grade chalcopyrite by column reactor, and community structure and dynamics were investigated by restriction fragment length polymorphism (RFLP). The results show that variation of pH was more obvious, and pH value was always higher than 1.8 in the bioleaching process. And 13.6% of copper was recovered within 60 days. RFLP results show that microbial community was dominated by L. ferriphilum in the initial stage, which occupied 81% of total prokaryotes. With the bioleaching process continues, the proportion of L. ferriphilum decreased slowly, which only had a proportion of 13% in the final stage. The proportion of S. thermotolerans and A. caldus were increase gradually, and the proportion was 32% and 23% respectively in the middle stage. S. thermotolerans was the dominant microorganism in the final stage, and the proportion was up to 79%. The research results could promote to understand bioleaching characteristics and behavior of moderately thermophilic microorganisms and provide referential experience for industrial application.

Key words:Bioleaching, Moderately thermophilic enrichment, Low-grade chalcopyrite, RFLP