Viruses of Acetoclastic Methanogens in Anaerobic Sludge Digesters

University Of Washington, Seattle WA

Investigators

Abstract

0930877 Meschke Towards the goal of characterizing the phage community within anaerobic digesters and identification of viral populations targeting the acetoclastic methanogens as their host, this project will address the following testable hypotheses: i) Phage capable of infecting acetoclastic methanogens is present in anaerobic digesters. ii) Phage molecular signatures will differ between infected acetoclast cultures showing impairment of methane generation and control cultures. iii) In infected pure cultures, phage/acetoclastic host population dynamics are related to impairment of methane production. The main thrust of this proposed research is to verify the role of viruses infecting acetoclasts in anaerobic process failure and to increase understanding of the presence and possible roles for phage on the microbial ecology of anaerobic digester systems. The above hypotheses will be addressed through: performance of viral infectivity studies with pure and enriched acetoclastic hosts; metagenomic analysis of viral size-fraction filtrates form anaerobic digesters, and development of qPCR methods for examining viral population dynamics in anaerobic acetoclastic populations. These tasks will be accomplished using: epifluorescence microscopy to enumerate viral particles; transmission electron microscopy to characterize viral morphologies and observe host cell damage; pulsed field gel electrophoresis for fingerprinting of viral populations in infected and control samples and isolation of viral DNA specific to acetoclast cultures showing impairment of methane production; pyrosequencing for analysis of metagenomic viral DNA; and qPCR for kinetic analysis of viral populations. The role of viruses in biotechnological processes and engineered systems is almost completely unexplored. Investigating the role of viruses of acetoclasts in anaerobic digesters may contribute to the understanding of the inability of some processes to work reliably, shift dominant populations, or fail. Overall, the results of the proposed study will provide building blocks for anaerobic digestion research that can help continue development of the fundamental understanding of the anaerobic microbial community, which is clearly needed for improved process design and operation. Exploration and greater characterization of digester communities will benefit society through enhanced energy (methane) generation, optimized biosolids production, and greater system stability, providing protection of human and ecological health. As anaerobic digesters are increasingly used for co-digestion to generate methane as a biofuel, a greater understanding of the role of viruses in these systems will help to ensure consistent performance. Graduate and undergraduate students will benefit directly from the proposed project in training and research experience. Efforts will be made to recruit undergraduate students from an underrepresented group with the assistance of the Engineering Advising and Diversity Center. This proposal will additionally offer mentoring to an early-career woman engineer. The results of this project will be disseminated to the greater scientific community through publication in peer-reviewed journals, and through presentation to inter-disciplinary audiences at campus seminars, and regional and national conferences