Today, more than three decades after the discovery of
bacterial permeases, it is still difficult to predict the
utilization pattern of sugars by E. coli despite the fact that
much is known about the genetics and biochemistry of
sugar transport and the subsequent metabolism. One can
conclude from our work that the extent of catabolite
repression is lessened or even absent at low glucose
concentrations. As a consequence, cells growing under
such conditions should be able to utilize many other
carbon substrates in combination with glucose, and also
immediately replace one growth substrate with another.
This is particularly relevant for understanding microbial
growth under environmental conditions where concentrations
of individual carbon sources are usually in the
pg 1-1 range and the total available carbon rarely exceeds
a few mg 1-1 (Munster & Chrbst, 1990)