UBC Theses and Dissertations
Microbial communities in field-based biological reactors treating mining-influenced water Rezadehbashi, Maryam
Metals, sulfate, nitrate and ammonia are the main chemical constituents of mining-influenced water (MIW). Biological reactors are attractive for low-cost treatment of MIW. But their successful performance relies on having microbial consortia with the metabolic potential to remove the contaminants of concern. This study undertook to explore the microbial communities in two types of field-based systems that successfully treat MIW: Semi-passive biochemical reactors (BCR) removing metals and sulfate; Active biological reactors removing ammonia and nitrate in the presence of metals. Pyrotag sequencing of 16S rRNA genes was performed for 80 samples from four BCRs. Although they were located at different mine sites, the BCRs shared several taxonomic groups. Sulfate-reducing microorganisms (SRM) were restricted to Deltaproteobacteria and only a few Clostridium genera. Core SRM were specialized, often poorly characterized genera, also prevalent at other metal-contaminated sites. The BCRs were populated by both acetate-consuming SRM and methanogens. SRM were more prevalent in some BCRs than methanogens, which are potential competitors. The structure of the microbial community in a BCR containing pulp and paper biosolids as carbon source was different from that in the other BCRs. Network analysis revealed that the putative keystone microorganisms in this BCR were phylogenetically different from those in the other BCRs. According to correlation analysis of these keystone microorganisms, a hypothetical model proposed that keystone microorganisms in BCR3 employ different mechanisms (antagonistic) than keystones in the other BCRs to regulate the structure of microbial community. The microbial communities within mine nitrogen-removing bioreactors shared several taxonomic groups with those in non-mine related nitrogen-removing facilities. The mine system selected for archaeal (rather than bacterial) ammonia oxidizer and denitrifying populations. The denitrifying population was enriched and a metagenomic study revealed genes encoding enzymes involved in metal metabolism (e.g. arsenite oxidation, mercury reduction) that were related to denitrifiers such as Rhodobacter sp., Thiobacillus sp., Burkholderia sp., Methylotenera sp., and Variovorax sp. Sequences related to taxa capable of aerobic denitrification, autotrophic denitrification, nitrifier denitrification, and anammox were found. The microbiology of the influent water had a significant impact on the microbial composition of the nitrogen-removing bioreactors.
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Attribution-NonCommercial-NoDerivs 2.5 Canada