Bioreactors can remove contaminants from wastewater while providing valuable products such as biofuels. Bioreactor function relies on an appropriate bacterial community structure for efficient conversion of waste. However, the bacterial community can be affected by bacteria present in the incoming waste stream. A less known way that the bioreactor bacterial community can be affected is by the presence of bacteriophage, viruses that only infect bacteria. Although phages are known to affect bacterial populations in marine environments, very little is known about bacteria-phage interactions in engineered bioreactors. The proposed research will evaluate the role of bacteriophage life-cycle on bioreactor bacterial communities based on the basic science of bacteria-phage interactions. This research will also shed light on whether phages participate in gene transfer with the bacterial communities. Results from this research will help define mechanisms for the removal of nitrogen, carbon, and pollutants from waste streams to protect ecological and human health, while producing valuable products like biofuels to enhance the Nation's energy security.<br/><br/>The overarching goal of this project is to study the genomic content of viruses infecting key bacteria from activated sludge processes (ASP) and anaerobic digester microbial communities in lab-scale reactors and anaerobic digesters. Three broad questions have been proposed: (1) What is the genomic content and diversity of viral communities infecting key ASP bacteria and microbiomes in organic waste valorization anaerobic bioprocesses?; (2) How does phage genomic content change with process configuration, and what is the role of phages during process upsets?; and (3) Are the bacteriophages present in ASP bioreactors and anaerobic digesters contributing to gene transfers between different prokaryotes? Three sets of lab scale reactors will be used to simulate commonly used treatment scenarios in the wastewater community. These reactors will be subjected to various external perturbations and disturbances to study bacteriophages dynamics in these reactors. High throughput sequencing of bacterial and phage DNA, followed by a genome extraction exercise, will allow the study of bacterial-phage interactions in engineered bioreactors. Overall, this project will answer several fundamental questions related to phages in engineered bioreactors and add to the science of wastewater treatment. The fundamental knowledge gained in this research will be applicable in other natural and engineered systems This research project will contribute to graduate and undergraduate education, and U.S graduate students will learn new techniques related to ecosystem research and virology.<br/><br/>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.