Description:

M&M&Ms: Microbial Ecology, MECs and Metagenomics

Abstract: Modern wastewater treatment systems are vital for protecting human and environmental health, however current treatment processes are energy intensive. Adoption of new technologies is slow in part due to a lack of understanding of how to engineer and control open microbial communities and a “once-through” treatment paradigm. I will discuss two projects focused on developing an “integrated microbial resource management” (IMRM) approach, i.e. the design and maintenance of microbial communities to enable comprehensive resource recovery.
Environmental bioprocesses depend on a complex microbial community whose dynamics are driven by a combination of environmental selection, immigration, historical and stochastic mechanisms. We used amplicon sequencing data collected from six full-scale activated sludge systems to demonstrate that community dynamics were highly reproducible and regionally synchronized, similar to previously studied natural lake ecosystems. Community dissimilarity varied more strongly with time rather than immigration source or operational characteristics, suggesting a significant influence of deterministic assembly mechanisms guided by seasonal temperature fluctuations. Moreover, rare and abundant taxa displayed varying sensitivity to deterministic and stochastic processes.
In addition to field-scale microbial ecology studies, I will discus the design and optimization of a lab-scale hybrid system for resource recovery from wastewater via bioelectrochemical hydrogen peroxide production and subsequent inorganic catalysis. In this work, we demonstrated tunable production of H2O2 in a microbial electrochemical cell (MEC) and optimized cathode buffer and hydraulic residence time for solubility and pH compatibility with the downstream catalytic system. We envision biologically derived H2O2 as part of an “urban biorefinery” system for upgrading waste feedstocks to valuable commodities. Ongoing metagenomic sequencing work is evaluating the impact of carbon source on the community structure, carbon utilization efficiency and resilience of the anode respiring community.

Biography:
Jim Griffin is a PhD candidate in the department of Chemical and Biological Engineering at Northwestern University. His research uses high throughput sequencing to investigate complex microbial communities in engineered and natural environments, with a particular interest in bioelectrochemical processes for resource recovery. He holds a B.S. in Chemical Engineering from MIT. In his spare time he is an amateur circus artist.