Microbial Metabolic Cooperation

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

Syntrophic bacteria are a group of poorly understood microorganisms that play essential roles in the recycling of all naturally occurring organic materials in environments without oxygen (anaerobic environments). Syntrophy refers to the mutually beneficial metabolic interactions of the participating bacteria. These bacteria work as members of small microbial teams that consume decaying plant and animal material and convert it back into the starting materials needed for photosynthesis by plants and algae. The syntrophic bacteria first break down and recycle small organic molecules such as fats, amino acids and small aromatic compounds and make acetic acid (vinegar), water and hydrogen gas. These syntrophic waste products are then used by a second group of microbes called methanogens to make more water plus carbon dioxide and methane. The latter can be harvested as a renewable energy source. By cooperating, both types of microbes are able to obtain energy and grow where neither could alone. This project will use a combination of molecular and biochemical methods to study the unique metabolic skills of each microbe and how they cooperate with one another to optimally recycle waste materials in nature. This knowledge will assist others to better describe and model the use of carbon on Earth and to predict how our ever-changing environment affects the maintenance of the Earth's life forms (the biosphere). This knowledge will also improve our ability to recycle unwanted waste materials in the environment. The knowledge obtained will be used develop new web-based and team-based activities that will promote enthusiasm for microbiology to lower and upper level microbiology undergraduates, including those from institutions with a large minority enrollment. Syntrophic metabolism is a microbial process found in nearly all anaerobic ecosystems yet very little is understood about the molecular, biochemical, or physiological basis of this essential ecological process. Understanding how syntrophic consortia composed of distinct types of bacterial and archaeal species operate at the metabolic and molecular levels is critical to describe and model global carbon cycling and ecosystem function. The hypothesis to be tested states that special metabolic and sensory/regulatory systems are used by syntrophic partners to accomplish their cooperative existence. The model syntrophic co-culture, Syntrophomonas wolfei and Methanospirillum hungatei, will be used to unravel the basic principles governing syntrophic partnership formation and maintenance. A combination of high-throughput technologies including genome-wide transcript and proteomic profiling will be used to identify the metabolic and regulatory networks involved in syntrophic fatty acid catabolism and to delineate other adaptations that may be required to maintain the syntrophic lifestyle. This will reveal the pathways operative in electron flow and hydrogen and/formate production from thermodynamically difficult reactions as well as special biochemical machinery and regulatory controls needed for syntrophic cooperation. These data will provide a foundation to predict and explore related processes in other multispecies microbial communities.