Effect of introduction of exogenous strain Leptospirillum ferriphilum YSK on functional gene expression, structure, and function of indigenous consortium during pyrite bioleaching

Abstract

Leptospirillum ferriphilum YSK was added to a native consortium of bioleaching bacteria including Acidithiobacillus caldus, A. thiooxidans, A. ferrooxidans, Sulfobacillus thermosulfidooxidans, Acidiphilium spp., and Ferroplasma thermophilum cultured in modified 9K medium containing 0.5% (W/V) pyrite. The bioleaching efficiency markedly increased. Changes in community structure and gene expression were monitored with real-time PCR and functional gene arrays. Dynamic changes that varied in different populations in the consortium occurred after the addition of L. ferriphilum YSK, with growth of A. caldus S1, A. thiooxidans A01, Acidiphillum spp. DX1-1 promoted the growth of Ferroplasma L1, inhibited that of S. thermosulfidooxidans ST, and exerted little effect on that of A. ferrooxidans CMS. Genes encoding ADP heptose, phosphoheptose isomerase, glycosyltransferase, biotin carboxylase, and protoheme ferrolyase from L. ferriphilum, acetyl-CoA carboxylase from Acidiphillum spp., and doxD from A. caldus were up-regulated in 0–20 h. Genes encoding lipid A disaccharide synthase LpxB, glycosyl transferase, and ADP heptose synthase from A. ferrooxidans were up-regulated in 0–8 h and then down-regulated in 8–20 h. Genes encoding ferredoxin oxidoreductase from Ferroplasma sp. were up-regulated in 0–4 h, down-regulated in 4–16 h, and again up-regulated in 16–20 h. CbbS from A. ferrooxidans was down-regulated in 0–20 h.