Summary: The effect of bicarbonate on the growth and product formation by a periodontopathic bacterium, , was examined in an anaerobic chemostat culture with fructose as the limiting nutrient. The chemostat cultures were run at dilution rates between 0·04 and 0·25 hand the maximum growth yield ( ) was estimated to be 40·3 and 61·7 g dry wt (mol fructose)in the absence and presence of bicarbonate, respectively. The major fermentation products in the absence of bicarbonate were formate, acetate, ethanol and succinate, with small amounts of lactate. The addition of bicarbonate to the medium resulted in a marked decrease in ethanol production and in a significant increase in succinate production. Washed cells possessed activity for the cleavage of formate to CO and H, which seemed to play a role in supplying CO for the synthesis of succinate in the absence of bicarbonate. The study of enzyme activities in cell-free extracts suggested that fructose was fermented by the Embden-Meyerhof-Parnas pathway. The values of and the efficiency of ATP generation (ATP-Eff) during fructose catabolism were estimated and higher values were obtained for the culture in the presence of bicarbonate: 20·2 g dry wt (mol ATP)and 30 mol ATP (mol fructose), respectively, versus = 15·1 and ATP-Eff = 2·7 in the absence of bicarbonate.


Article metrics loading...

Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error