Bacterial diversity analysis of moderately thermophilic microflora enriched by different energy sources

Abstract:

Bacterial biodiversities of three moderately thermophilic bioleaching microfloras grown at 50℃ on media with pyrite, chalcopyrite, and pure ferrous iron supplemented with sulfur as energy sources were investigated respectively. The 16S rRNA genes of the microorganisms in the cultures flasks were PCR amplified and cloned to identify the bacterial species by comparative sequence analysis, the structural differences of microfloras enriched by different energy sources were compared. A total of 303 clones were recovered and evaluated by restriction fragment length polymorphism (RFLP) analysis. Cluster analysis identified 29 unique RFLP patterns, and the inserted 16S rRNA genes sequences were determined and for phylogenetic analysis. Most of sequences obtained were similar (89.1%～99.7%) to the 16S rRNA gene sequences of the reported bioleaching microorganisms. The species identified from the flasks during bioleaching of pyrite, pure ferrous iron supplemented with sulfur, and chalcopyrite were closely related to Acidithiobacillus caldus, Sulfobacillus thermotolerans, Sulfobacillus thermosulfidooxidans, Leptospirillum ferriphilum, two uncultured forest soil bacterium clones and one uncultured proteobacterium clone. Among these bacteria, Acidithiobacillus caldus, Sulfobacillus thermotolerans and Leptospirillum ferriphilum were the dominant bacterial species. L. ferriphilum was the most dominant species in microfloras enriched in media with pyrite and ferrous iron supplemented with sulfur as energy sources, the abundance were 53.8% and 45.9% respectively. In the culture with chalcopyrite as energy sources, S. thermotolerans had the highest abundance of 70.1%.