Metabolic footprinting of the anaerobic bacterium Fusobacterium varium using 1H NMR spectroscopy

Abstract

Metabolic footprinting of the anaerobic bacterium Fusobacterium varium demonstrated the accumulation of six carboxylic acids as metabolic end-products and revealed specific growth requirements and utilization capabilities towards amino acids. Guided by (1)H NMR determinations of residual amino acids in spent medium, a modified chemically defined minimal medium (CDMM*) was developed by minimizing the amino acid composition while satisfying nutritional requirements to support abundant growth of F. varium. Quantitative determinations of carboxylate salts and residual substrates were readily performed by (1)H NMR analysis of lyophilized residues from CDMM* cultures without interference from initial medium components. Only small concentrations of alanine, arginine, glycine, isoleucine, leucine, methionine, proline and valine were required to support growth of F. varium, whereas larger quantities of aspartate, asparagine, cysteine, glutamine, glutamate, histidine, lysine, serine and threonine were utilized, most likely as energy sources. Both bacterial growth and the distribution of carboxylate end-products depended on the composition of the chemically defined medium. In cultures provided with glucose as the primary energy source, the accumulation of butyrate and lactate correlated with growth, consistent with the regeneration of reduced coenzyme formed by the oxidative steps of glucose catabolism.

Oxygen Affects Gut Bacterial Colonization and Metabolic Activities in a Gnotobiotic Cockroach Model

“…Such shifts toward increased lactate formation in the presence of nonlimiting concentrations of glucose have also been described for chemostat cultures of Klebsiella aerogenes (70) and several Streptococcus spp. (71,72) and are in agreement with the production of lactate by Fusobacterium varium grown at high glucose concentrations (73). In conventional cockroaches, the accumulation of lactate was less pronounced, which suggested that the normal gut microbiota, like that of termites, comprises active lactate-consuming populations (12).…”

Fusobacterium Is Associated with Colorectal Adenomas

“…Altered colonic pH could affect metabolic activity, absorption of short-chain fatty acids (SCFA), and composition of gut microflora and mucosal cell proliferation [34]. Walker et al observed that even a single unit change in pH affected the host microbial community composition as well as production of SCFA, especially among butyrate-producing species [35], a group within which Fusobacterium is included [36]–[39]. While most bile acids aid solubilization of lipids and facilitate nutrient absorption, some are transformed by intestinal bacteria into toxic secondary bile acids in the colon [40].…”

Impact of diets with a high content of greaves-meal protein or carbohydrates on faecal characteristics, volatile fatty acids and faecal calprotectin concentrations in healthy dogs

“…Interestingly, the faecal samples from dogs fed the greaves-meal diet had a high preponderance of Fusobacteriales bacteria [32]: an order of bacteria that has been suspected to play a pathogenic role in human intestinal inflammation [34-36]. Therefore, one could hypothesize that Fusobacteria could produce branched VFAs and valeric acid from protein break-down products [53]. Moreover, some Fusobacteria could act as pathogens, which may cause intestinal inflammation that would result in increased faecal calprotectin levels.…”