Fermentation of various soluble carbohydrates by rumen micro-organisms with particular reference to methane production

Abstract

1. The fermentation of twenty-six different carbohydrates was studied in an artificial rumen.2. The rates of fermentation varied widely, but except in the case of rhamnose the amount of methane produced was usually related to the amount of carbohydrate fermented (6.0 Cal/ 100 cal of substrate). There was also a correlation between the amount of carbohydrate fermented and the amounts of steam-volatile acids formed.3. Glucose, fructose and sucrose were fermented rapidly but mannitol, sorbitol, glucuronic and galacturonic acids, glucosamine, D(–)-arabinose, ribose, sorbose, trehalose and starch were fermented very slowly or not at all. L(+)-Arabinose, xylose, galactose, mannose, cellobiose, maltose, lactose, raffinose, inulin, xylan and pectin were fermented at appreciable rates.4. The methyl-pentose, rhamnose, was fermented but no methane was produced. Fucose was fermented very slowly.5. The fermentation of sucrose and its constituent hexoses was characterized by a transient accumulation of lactate. The fermentation of rhamnose and of glucosamine was accompanied by permanent accumulation of lactate. No measurable amounts of lactate were produced when any of the other sugars were fermented.