Aspartate Dissimilation Reactions of Rumen Bacteria

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Abstract
The dissimilation of aspartate by mixed suspensions of bovine rumen bacteria was studied in detail. The feasibility of succinate, malate, fumarate, pyruvate, lactate, alpha-alanine and beta-alanine as intermediates was considered by manometric, inhibition and analytical methods. Only succinate is similar to aspartate in respect to total CO2 production (105-112[mu]l. or 1.0-0.96 g. per mole of substrate). CO2 production from succinate occurs at a rate higher (QcO2 = 10) than that from aspartate (QcO2 = 7.8). Similar relationships were obtained when cell-free extracts were employed. Both aspartate and succinate are converted to propionate, the main end product. Formation of acetate and eventually butyrate from aspartate occurs during prolonged incubation. Inhibition of CO2 production from aspartate and succinate is approx. the same at various concn. of malonate, viz., 0.3 [image]malonate caused an 80-90% inhibition. The principal pathway appears to be a deamination to succinate, decarboxylation to propionate and further conversion to acetate and butyrate.