Unexpected metabolic versatility discovered using new high-throughput genetic approaches in a model methanogen

Abstract

Microorganisms known as methanogens produce most of the methane on Earth and areglobally distributed in anoxic (i.e., oxygen-free) environments such as freshwater and marine sediments, wastewater treatment facilities, and the digestive tracts of ruminants. Despite acknowledgement of their broad distribution across a wide range of anoxic environments, technical challenges in culturing and adaptation of genetic tools have slowed our understanding of the mechanisms essential for survival in the absence of oxygen. My thesis research has expanded and advanced the application of the genetic tools available for methanogens and furthered our understanding of how methanogens interact with other organisms and their environment. This thesis demonstrates the development and adaptation of genetic approaches to identify metabolic mechanisms contributing to the fitness of Methanococcus maripaludis as a model for methanogenic archaea in general. In this introduction, I will discuss our current understanding of methanogenesis and the metabolic capabilities of hydrogenotrophic methanogens while also highlighting gaps in our understanding. In subsequent chapters I will describe the genetic approaches employed and gaps I have filled in our understanding of methanogen metabolic capabilities using the model methanogen Methanococcus maripaludis.