GLUTAMATE CATABOLISM AND SUCCINATE PRODUCTION IN Fusobacterium varium

Abstract

Important bacteria located in the human gut contribute to human health and disease. Further understanding of metabolism in the gut bacterium F. varium was developed in this thesis. The use of [13C5]glutamate and the analysis of 13C-13C coupling patterns observed by NMR spectroscopy established that glutamate was catabolized by two different pathways. The methylaspartate pathway was utilized when cobalt ions were available while the hydroxyglutarate pathway functioned when cobalt ions were not available illustrating environmental control over pathway selection. Succinate, a metabolic product of F. varium, was obtained in increased yield when cultures were supplemented with fumarate. Factors affecting succinate production were examined using cell suspensions. Suspensions of cells grown on fumarate-supplemented medium catalyzed high conversions of fumarate to succinate when supplied with sufficient carbon source. Glucose, sorbitol and glycerol were suitable carbon sources and efficient conversions were obtained at fumarate concentrations up to 300 mM. At high fumarate concentrations, retention of succinate inside the cells noticeably reduced the levels in suspensions fluids. This approach has potential for the production of biosuccinate acid, a substrate used for the sustainable manufacture of commodity chemicals.