Ammonia-utilizing enzymes of adherent bacteria in the sheep's rumen

Abstract

In experiments on 6 sheep the authors found the following enzyme activities in bacteria in the rumen fluid, bacteria adhering to the epithelium of the rumen wall and bacteria adhering to food particles in the rumen (given in nkat X g-1 bacterial dry weight): GDH (NADH): 725 +/- 165, 558 +/- 127, 661 +/- 153; GDH (NADPH): 558 +/- 338, 255 +/- 88, 565 +/- 139; GOAT (NADH): 46 +/- 23, 67 +/- 31, 66 +/- 14; GOGAT/NADPH: 58 +/- 27, 56 +/- 15, 65 +/- 29; GS: 153 +/- 65, 69 +/- 35, 71 +/- 32; ALT: 71 +/- 25, 43 +/- 20, 52 +/- 11; AST: 52 +/- 12, 33 +/- 16, 28 +/- 15. The results show that, except for GDH (NADPH), there were no significant differences between the given enzyme activities in the rumen fluid and in bacteria adhering to the rumen wall and to food. Adherent rumen bacteria have the same potential possibilities as the rumen fluid bacteria for the utilization of ammonia, particularly for the synthesis of glutamic acid, glutamine, alanine and aspartic acid, with the above enzymes as catalysts. By means of the GS/GOGAT system, adherent rumen bacteria can probably synthesize glutamic acid in the presence of a limited NH3 concentration in the rumen.