RII Track-4:NSF Engineering mixed microbial communities & bioreactor configurations to optimize biotransformation processes for metal and metalloid bioremediation and biorecovery

Waste streams from agricultural run-off and industries such as mining typically contain pollutants like metals and metalloids (M&M), which can be toxic and pose a threat to the environment and health. The removal and recovery of M&M from wastewater is crucial to prevent environmental contamination and to develop a more sustainable use of resources. This project proposes to exploit the ability of microbes to transform toxic and water-soluble forms of M&M into non-toxic forms which can be recovered as value-added products (e.g., metallic nanoparticles that can have multiple applications).

Under the concept of "together is better", we plan to use mixed microbial communities of fungi and bacteria (relatively unexplored communities) to develop bioreactor systems for metal- and metalloid- biotransformation processes; by increasing the number and diversity of partners in a microbial community we can create more resilient, tolerant, and stable communities with improved biotransformation processes compared to their individual counterparts. The proposed work will (i) provide key fundamental knowledge regarding microbial interactions between fungi and bacteria in mixed microbial communities, a topic of interest to better understand the microbial system in nature; and (ii) lay down the foundation for the development of improved systems for the removal and recovery of harmful M&M from waste streams, which has transformative potential and can revolutionize both bioremediation technologies and future biomanufacturing.

This project envisions using multi-domain mixed microbial communities (MMCs), specifically the relatively unexplored fungal-bacterial biofilms, for improved biotransformation and bioremediation of metals and metalloids (M&M) from waste streams and biorecovery of value-added products (e.g., metallic nanoparticles) beneficial to society. This project will address some of the main challenges in using MMCs for bioprocessing: the poor understanding of MMCs and the lack of bioreactors to successfully cultivate MMCs and maintain stable bioprocessing.

Thus, the goal of this project is to develop and optimize MMCs and bioreactor systems for improved bioprocessing of M&M for bioremediation and biorecovery. As a proof of concept, selenium (Se, a common metalloid found in acid mine drainage) will be used as an example to assess the potential use of the proposed fungal-bacterial biofilm systems for M&M bioremediation and biorecovery in this project.

Three main tasks are proposed: (1) establishing fungal-bacterial biofilms with relevant environmental microorganisms and characterizing their structural and mechanical properties using a combination of cutting-edge techniques including magnetic tweezers, shear rheometry, and optical coherence tomography; (2) developing Membrane Biofilm Reactors (MBfR), an emergent technology based on the use of membranes that transfer gas to a biofilm growing on the membrane, to support fungal-bacterial biofilm establishment; and (3) assessing and optimizing reactor performance and stability of MBfRs with fungal-bacterial biofilms for the removal of Se and its recovery. Understanding and controlling microbial interactions in MMCs and developing improved multi-domain bioreactor systems is key to building a sustainable future minimizing pollution and to utilizing waste streams for the recovery of the generation of high-value products.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.