Microbial community and metabolic pathway succession driven by changed nutrient inputs in tailings: effects of different nutrients on tailing remediation

Mingjiang Zhang,Guangyuan Wang,Xingyu Liu,Yibin Li,Zining Wang,Jiankang Wen

doi:10.1038/s41598-017-00580-3

Mingjiang Zhang, Guangyuan Wang + Show 4 more

Open Access

https://doi.org/10.1038/s41598-017-00580-3

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Abstract

To solve the competition problem of acidophilic bacteria and sulfate-reducing bacteria in the practical application of mine tailing bioremediation, research into the mechanisms of using different nutrients to adjust the microbial community was conducted. Competition experiments involving acidophilic bacteria and sulfate-reducing bacteria were performed by supplementing the media with yeast extract, tryptone, lactate, and glucose. The physiochemical properties were determined, and the microbial community structure and biomass were investigated using MiSeq sequencing and qRT-PCR, respectively. Four nutrients had different remediation mechanisms and yielded different remediation effects. Yeast extract and tryptone (more than 1.6 g/L) promoted sulfate-reducing bacteria and inhibited acidophilic bacteria. Lactate inhibited both sulfate-reducing and acidophilic bacteria. Glucose promoted acidophilic bacteria more than sulfate-reducing bacteria. Yeast extract was the best choice for adjusting the microbial community and bioremediation, followed by tryptone. Lactate kept the physiochemical properties stable or made slight improvements; however, glucose was not suitable for mine tailing remediation. Different nutrients had significant effects on the abundance of the second enzyme of the sulfate-reducing pathway (p < 0.05), which is the rate-limiting step of sulfate-reducing pathways. Nutrients changed the remediation effects effectively by adjusting the microbial community and the abundance of the sulfate-reducing rate-limiting enzyme.

Highlights

According to the official statistics from the state administration of work safety in 2012, approximately 12,273 mine tailings have generated eight billion tons of mine waste in China[1]
In the sulfate-reducing bacteria (SRB) remediation process, sulfate is reduced to hydrogen sulfide, the dissolved metal ions are precipitated as metal sulfides, and the concentration of heavy metal ions in solution decreases[10, 11]
Solution pH results revealed that yeast extract at 0.4 g/L inhibited the decrease in pH, whereas yeast extract at more than 0.8 g/L increased the solution pH to neutral

Summary

Introduction

According to the official statistics from the state administration of work safety in 2012, approximately 12,273 mine tailings have generated eight billion tons of mine waste in China[1]. The decreases in the ORP in the control and glucose-supplemented groups resulted from anaerobic conditions because some acidophilic bacteria and SRB can reduce sulfate and decrease the ORP with anaerobic conditions[19]. These results indicated that the supplemented yeast extract and tryptone could remove the dissolved sulfur and iron and could improve the tailing environment significantly. Supplementation of yeast extract, tryptone, and glucose significantly elevated the microbial biomass (p < 0.05); the biomass correlated with the nutrient concentration (p < 0.05).

Results

Conclusion