ABSTRACT
The metabolism of carbohydrates by microorganisms is accomplished via a number of metabolic routes. The aerobic fungi form a homogeneous group with respect to sugar catabolism, ultimately producing CO2 and H2O and maintaining a redox balance via mitochondrial electron transport. Anaerobic rumen chytridiomycetes, of which three genera have been isolated in pure culture Neocallimastix spp., Sphaeromonas spp., and Piromonas spp, constitute a ubiquitous population of fungi inhabiting the rumen of wild and domestic ruminants, including cattle, sheep, and reindeer, and the hindgut of other large herbivores, including the horse, elephant, rhinoceros. The mechanism of acetate formation by the parasitic trichomonads and the symbiotic rumen ciliates differs in the mechanism by which energy is conserved in the form of adenosine triphosphate. The amount of glycerol produced by the rumen fungi has not been determined, but the published fermentation product balance of various Neocallimastix spp.
