The electrochemical aspects of some biochemical systems—X. The anomalous behaviour of E. coli with mixed substrates—2

Abstract

In a previous study the metabolism of mixed substrates by E. coli harvested in the stationary phase of their growth cycle after being grown in a broth containing glucose was investigated using the “coulokinetic” technique. It was found with the mixtures of glucose and pyruvate, fructose and pyruvate, and glucose and fructose, that glucose, pyruvate, and glucose respectively was consumed more rapidly by the micro-organisms. The present investigation was conducted using E. coli harvested after growth in a fructose medium. With a mixture of glucose and pyruvate the micro-organisms reversed their previously observed behaviour and demonstrated a preference for the utilization of pyruvate. These E. coli showed no pronounced difference in their utilization of the mixture of fructose and pyruvate. The bacteria grown on fructose still utilized glucose more rapidly in the mixture of glucose and fructose. However in this instance both substrates were utilized simultaneously rather than consecutively.