Energy difference in metabolism between glucose and acetate in chemostat culture of Azotobacter vinelandii

Abstract

Following the previous chemostat cultures of Azotobacter vinelandii using glucose as the sole carbon source, another work, replacing glucose with acetate, is presented in this paper. The experimental fact here that RQ values were from 0.6 to 0.8 in a range of dilution rate D, extending from 0.114 to 0.327hr-1, suggests that glyoxylate cycle as an anaplerotic pathway predominates over tricarboxylic acid cycle.The yield factor for acetate, YX/S g cell/g acetate, decreased from 0.15 to 0.06 with an increase in dissolved oxygen concentration, [D.O.], in an acetate medium. The inhibitory effect of [D.O.] on the YX/S values was similar to that in the previous study on glucose. However, the value of YX/S for acetate was smaller than that for glucose. Assuming that the value of YATP is constant, irrespective of acetate or glucose, the difference in YX/S values between the carbon sources was ascribed to that in moles of ATP required to phosphorylate one gram of acetate and glucose.