Worms, bacteria, and micronutrients: an elegant model of our diet

•Micronutrients affect human health either directly or indirectly via gut microbiota. •Caenorhabditis elegans and its bacterial diet can be used as a model for both effects. •The worm and its bacterial diet provide a powerful interspecies systems biology model. •The worm/bacteria model connects vitamins B9 and B12 to animal physiology and metabolism. Micronutrients are required in small proportions in a diet to carry out key metabolic roles for biomass and energy production. Humans receive micronutrients either directly from their diet or from gut microbiota that metabolize other nutrients. The nematode Caenorhabditis elegans and its bacterial diet provide a relatively simple and genetically tractable model to study both direct and microbe-mediated effects of micronutrients. Recently, this model has been used to gain insight into the relationship between micronutrients, physiology, and metabolism. In particular, two B-type vitamins, vitamin B12 and folate, have been studied in detail. Here we review how C. elegans and its bacterial diet provide a powerful interspecies systems biology model that facilitates the precise delineation of micronutrient effects and the mechanisms involved. Micronutrients are required in small proportions in a diet to carry out key metabolic roles for biomass and energy production. Humans receive micronutrients either directly from their diet or from gut microbiota that metabolize other nutrients. The nematode Caenorhabditis elegans and its bacterial diet provide a relatively simple and genetically tractable model to study both direct and microbe-mediated effects of micronutrients. Recently, this model has been used to gain insight into the relationship between micronutrients, physiology, and metabolism. In particular, two B-type vitamins, vitamin B12 and folate, have been studied in detail. Here we review how C. elegans and its bacterial diet provide a powerful interspecies systems biology model that facilitates the precise delineation of micronutrient effects and the mechanisms involved. measurable physiological and phenotypic properties that affect the health of an animal and the population. Examples include brood size, developmental rate, and lifespan. the rate at which Caenorhabditis elegans proceeds through the larval stages (L1, L2, L3, and L4) to the young adult stage and then to adulthood. RNA interference to inhibit gene expression. In C. elegans, double-stranded RNA (dsRNA) complementary to the targeted mRNA on one strand is given to worms by feeding a bacterial strain that carries the dsRNA in a plasmid vector. fatty acids with five or fewer carbons, including formic- (one carbon), acetic- (two carbons), propionic- (three carbons), butyric- (four carbons), and valeric- (five carbons) acid. SCFAs are products of fatty acid beta oxidation as well as bacterial fermentation, for example, in the human colon. one of the water-soluble B vitamins that is important for blood formation and normal functioning of nerves. It is the most complicated vitamin, with a cobalt atom placed at the center of a tetra-pyrrole ring. Depending on the group (R) attached to this cobalt atom, it takes different forms, which include hydroxocobalamin (R = OH), adenosylcobalamin (R = adenosyl group), and methylcobalamin (R = methyl group). another water-soluble B vitamin that is important for cell division and growth. Folic acid is activated when converted to dihydrofolate, which is transformed into tetrahydrofolate, the active form in one carbon pool by folate (also known as the folate cycle; see Figure 3 in main text). Different derivatives of tetrahydrofolate exist including 10-formyltetrahydrofolate, 5,10-methenyltetrahydrofolate, 5,10-methylenetetrahydrofolate, and 5-methyltetrahydrofolate.