Data from: Natural variation in preparation for nutrient depletion reveals a cost-benefit tradeoff

Maximizing growth and survival in the face of a complex, time-varying
environment is a common problem for single-celled organisms in the wild.
When offered two different sugars as carbon sources, microorganisms first
consume the preferred sugar, then undergo a transient growth delay, the
“diauxic lag,” while inducing genes to metabolize the less preferred
sugar. This delay is commonly assumed to be an inevitable consequence of
selection to maximize use of the preferred sugar. Contrary to this view,
we found that many natural isolates of Saccharomyces cerevisiae display
short or nonexistent diauxic lags when grown in mixtures of glucose
(preferred) and galactose. These strains induce galactose utilization
(GAL) genes hours before glucose exhaustion, thereby “preparing” for the
transition from glucose to galactose metabolism. The extent of preparation
varies across strains, and seems to be determined by the steady-state
response of GAL genes to mixtures of glucose and galactose rather than by
induction kinetics. Although early GAL gene induction gives strains a
competitive advantage once glucose runs out, it comes at a cost while
glucose is still present. Costs and benefits correlate with the degree of
preparation: strains with higher expression of GAL genes prior to glucose
exhaustion experience a larger upfront growth cost but also a shorter
diauxic lag. Our results show that classical diauxic growth is only one
extreme on a continuum of growth strategies constrained by a cost–benefit
tradeoff. This type of continuum is likely to be common in nature, as
similar tradeoffs can arise whenever cells evolve to use mixtures of
nutrients.