FERMENTATION OF RADIOLABELED SUBSTRATES BY BATCH CULTURES OF CECAL MICROFLORA MAINTAINED IN A CONTINUOUS-FLOW CULTURE

Glucose- and lactose-based media containing either C-14-labelled gluco se, galactose, lactose or lactic acid were inoculated with anaerobic c ultures of chicken caecal bacteria maintained for 121 d in a continuou s-flow (CF) culture. The culture was previously shown to reduce Salmon ella colonization in the caeca of chicks inoculated with the culture a nd the reduction was associated with increases in volatile fatty acids . The distributions of C-14 were determined among the fermentation pro ducts, especially acetic, propionic and lactic acids. After 12 h of in cubation and fermentation, variations were observed in the total amoun ts of C-14, from each C-14-labelled substrate, detected as acetic and propionic acids in the glucose- and lactose-based media, respectively: 92.9 and 89.4% of C-14-glucose, 77.0 and 44.0% of C-14-galactose, 0.0 and 76.9% of C-14-lactose, and 76.5 and 93.2% of lactic acid in the t wo media, respectively. The results from this study indicate that carb ohydrate metabolism by the CF culture was a major source of acetic and propionic acids and that lactic acid was an important metabolic inter mediate for the synthesis of the volatile fatty acids.