not been reported in this organism to date. As such it is classified as a BSL-1 organism by the ATCC. Metabolism This chemoorganotrophic anaerobe utilizes various sugars as electron donors to produce carbon dioxide and acetate through some rare metabolic processes. The main electron donors include carbohydrates such as pyruvate, glucose, fructose, galactose, maltose, cellobiose, lactose, arabinose, maltose, ribose, xylose, salicin, and esculin, making it well adapted to a habitat where complex organic compounds are being degraded, such as the rumen of a cow. This organism actually has three major electron acceptors: formate, methoxymonobenzenoids, or methanogens. Its first option is the reduction of formate to acetate, giving S. sucromutans its title as an acetogen. The unique aspect of its acetate production is that it can synthesize many of these organic products from one-carbon compounds. Another set of electron acceptors consists of the methoxyl groups on benzenoid compounds, converting those groups into hydroxyl groups. Below is a table of potential electron acceptors and to what S. sucromutans reduces them. Its electron acceptors were characterized by its discoverers Krumholz and Bryant, who used ultraviolet absorbance to measure caffeate disappearance, thin layer chromatography to identify benzenoids, and the phenol sulphuric method for determining carbohydrate content. Its third option is to donate these terminal electrons to a methanogen such as Methanobrevibacter smithii by utilizing hydrogen, as H2, or formate as an electron carrier. S. sucromutans can only grow utilizing sugars and pyruvate if the hydrogen partial pressure is maintained at a low value. In addition, it requires ruminal fluid in order to maintain optimal growth. The complex and diverse system within an animal’s ruminal biome provides a steady nutrient supply from the host’s breakdown of food and the processes of other microbes. Ecology S. sucromutans is the most numerous ruminal bacteria in its environment that demethylates methoxy groups of monoaromatic compounds. Similar to many microbes that live within the rumen of grazing hosts, S. sucromutans depends on the steady supply of nutrients from the animal’s breakdown of food or the products of other neighboring microbes. Krumholz and Bryant found that S. sucromutans grew best in a coculture with fructose, formate, and Methanobrevibacter smithii. The fact that it grew better in a coculture than even by itself with these nutrients demonstrates further that this organism is well adapted to a complex microbial community. In addition, S. sucromutans was found to be a dominant OTU in