Abstract

Bioremediation systems represent an environmentally sustainable approach to degrading industrially generated thiocyanate (SCN⁻), with low energy demand and operational costs and high efficiency and substrate specificity. However, heavy metals present in mine tailings effluent may hamper process efficiency by poisoning thiocyanate-degrading microbial consortia. Here, we experimentally tested the tolerance of an autotrophic SCN⁻-degrading bacterial consortium enriched from gold mine tailings for Zn, Cu, Ni, Cr, and As. All of the selected metals inhibited SCN⁻ biodegradation to different extents, depending on concentration. At pH of 7.8 and 30 °C, complete inhibition of SCN⁻ biodegradation by Zn, Cu, Ni, and Cr occurred at 20, 5, 10, and 6 mg L⁻¹, respectively. Lower concentrations of these metals decreased the rate of SCN⁻ biodegradation, with relatively long lag times. Interestingly, the microbial consortium tolerated As even at 500 mg L⁻¹, although both the rate and extent of SCN⁻ biodegradation were affected. Potentially, the observed As tolerance could be explained by the origin of our microbial consortium in tailings derived from As-enriched gold ore (arsenopyrite). This study highlights the importance of considering metal co-contamination in bioreactor design and operation for SCN⁻ bioremediation at mine sites.

Key points

• Both the efficiency and rate of SCN⁻ biodegradation were inhibited by heavy metals, to different degrees depending on type and concentration of metal.

• The autotrophic microbial consortium was capable of tolerating high concentrations of As, potential having adapted to higher As levels derived from the tailings source.

中文翻译：

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重金属对矿山尾矿富集的自养微生物财团对硫氰酸盐生物降解的影响

摘要

生物修复系统代表一种环境可持续的方法，工业上降解产生硫氰酸（SCN ^- ），具有低能量需求和操作成本和高效率和底物特异性。但是，矿山尾矿废水中存在的重金属可能会通过使降解硫氰酸盐的微生物联盟中毒而影响加工效率。在这里，我们实验测试自养SCN的宽容^- -degrading从金矿尾矿为锌，铜，镍，铬，和作为富含细菌的财团。所有选择的金属的抑制SCN ^-生物降解到不同的程度，这取决于浓度。在7.8和30℃下的pH值，SCN的完全抑制^-Zn，Cu，Ni和Cr分别在20、5、10和6 mg L ^-1发生生物降解。这些金属的较低浓度SCN的率下降^-生物降解，具有相对较长的滞后时间。有趣的是，微生物聚生体耐受由于甚至在500毫克的L ^-1，虽然两者的速度和SCN的程度^-生物降解受到了影响。潜在地，观察到的As耐受性可以用我们的微生物财团起源于富含As的金矿石（毒砂）的尾矿中来解释。这项研究强调考虑到生物反应器的设计和操作SCN金属共同污染的重要性^-在矿区生物治理。

关键点

• SCN的的效率和速率^- 生物降解是由重金属抑制，以根据类型和金属的浓度不同的程度。

•自养微生物协会能够耐受高浓度的砷，其潜力已适应来自尾矿来源的较高砷含量。