Community Structure and Microbial Activity of Sulfate Reducing Bacteria in Wastewater Biofilms and Mature Fine Tailings Analyzed by Microsensors and Molecular Biology Techniques

• Author / Creator

  Liu,Hong

• Sulfate reducing bacteria (SRB) play a significant role in complex microbial environments such as wastewater biofilms and mature fine tailings (MFT). A unique characteristic of these complex microbial environments is that stratified structure containing both oxic and anoxic zones could be formed; the anoxic zones were expected to provide microenvironment for the growth and function of SRB. SRB utilize sulfate as a terminal electron acceptor during dissimilatory sulfate reduction for the degradation of organic compounds. However, hydrogen sulfide (H2S) gas is generated during the biological sulfate reduction process. The produced toxic H2S itself is one of the concerns; in addition, the generated H2S leads to an increase in oxygen (O2) consumption due to the internal re-oxidation of H2S. To address the SRB problem in municipal wastewater, in MFT, and in oil sands process-affected wastewater (OSPW) generated from the industrial extraction of bitumen, the functional diversity and in situ activity of SRB were investigated in O2 based membrane aerated biofilm (MAB), MFT, and biofilm grown in OSPW. H2S microsensor was used for in situ measurements of SRB microbial activity. PCR-DGGE-FISH (polymerase chain reaction-denaturing gradient gel eletrophoresis-fluroscence in situ hybridization) and DGGE-qPCR were applied to investigate the functional diversity and abundance of SRB in biofilms and MFT, respectively. In the MAB sample, the O2 concentration profile in MAB revealed the presence of oxic and anoxic zones. The H2S concentration profile showed that H2S was produced in the upper region of the biofilm and penetrated 285 µm below the interface between biofilm and bulk liquid, indicating a high activity of SRB in this region. DGGE of the PCR-amplified dissimilatory sulfite reductase subunit β (dsrB) gene and FISH showed an uneven spatial distribution of SRB communities in terms of functional diversity and biomass. The maximum SRB biomass was located in the upper biofilm. In the MFT sample, a higher diversity of SRB was present and more H2S was produced in gypsum amended MFT than in unamended MFT. Based on the combined techniques, a higher sulfate reduction activity in gypsum amended MFT than in unamended MFT was indicated; in addition, more H2S was produced in the deeper regions of the MFT samples. In the OSPW biofilm sample, multispecies biofilm in OSPW was developed on engineered biocarriers and was capable of simultaneous removal of chemical oxidation demand (COD), sulfate, and nitrogen from OSPW. H2S was observed in the deeper anoxic zone from around 750 μm to 1000 μm below the interface, revealing in situ sulfate reduction in the deeper zone of the stratified biofilm.

• Subjects / Keywords

  • Molecular Biology
  • Sulfate Reducing Bacteria
  • Microbial Activity
  • Community Structure
  • Microsensors

• Graduation date

  Spring 2015

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3FH4K

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.