Modelling microbial adaptation to changing availability of substrates
Brandt, B.W., Kelpin, F.D.L., Leeuwen, I.M.M. van and Kooijman,
Modelling microbial adaptation to changing availability of substrates.
Water Research, 38: 1003 - 1013.
In their natural environment microorganisms encounter changes in
substrate availability, involving either nutrient concentrations or
nutrient types. They have to adapt to the new conditions in order to
survive. We present a model for slow microbial adaptation, involving
the synthesis of new enzymes, in response to changes in the
availability of substitutable substrates. The model is based on
reciprocal (or mutual) inhibition of expression of both the
substratespecific carriers and the associated assimilatory
machinery. The inhibition kinetics is derived from the kinetics of
synthesizing units. An interesting property of the adaptation model is
that the presence of a single limiting resource results in a constant
maximum specific substrate consumption rate for fully adapted
microorganisms. Because the maximum specific consumption rate is not a
function of substrate concentration, for growth on one substrate, the
Monod and Pirt models for instance are still valid. Other adaptation
models known to us do not ful l this property. The simplest version of
our model describes adaptation during diauxic growth, using only one
preference parameter and one initial condition. The applicability of
the model is exempli ed by tting it to published data from diauxic
support is available for this paper.