Genome-resolved metagenomics of an autotrophic thiocyanate-remediating microbial bioreactor consortium

摘要

Industrial thiocyanate (SCN-) waste streams from gold mining and coal coking have polluted environments worldwide. Modern SCN- bioremediation involves use of complex engineered heterotrophic microbiomes; little attention has been given to the ability of a simple environmental autotrophic microbiome to biodegrade SDI-. Here we present results from a bioreactor experiment inoculated with SCN- -loaded mine tailings, incubated autotrophically, and subjected to a range of environmentally relevant conditions. Genome-resolved metagenomics revealed that SCN- hydrolase-encoding, sulphur oxidizing autotrophic bacteria mediated SCN- degradation. These microbes supported metabolically dependent non-SCN--degrading sulphur-oxidizing autotrophs and non-sulphur oxidizing heterotrophs, and "niche" microbiomes developed spatially (planktonic versus sessile) and temporally (across changing environmental parameters). Bioreactor microbiome structures changed significantly with increasing temperature, shifting from Thiobacilli to a novel SCN- hydrolase-encoding gammaproteobacteria. Transformation of carbonyl sulphide (COS), a key intermediate in global biogeochemical sulphur cycling, was mediated by plasmid-hosted CS2 and COS hydrolase genes associated with Thiobacillus, revealing a potential for horizontal transfer of this function. Our work shows that simple native autotrophic microbiomes from mine tailings can be employed for SCN- bioremediation, thus improving the recycling of ore processing waters and reducing the hydrological footprint of mining. (C) 2019 Elsevier Ltd. All rights reserved.