It is commonly conjectured that diauxic growth enables cells "to increase their fitness by optimizing growth rates in natural environments providing complex mixtures of nutrients" [ 2].
However, in our study we did not aim to optimize growth rates and cell densities for the individual species under study: our goal was to compare temperature and irradiance effects on PUFA composition in dilute cultures under standardized, nutrient replete conditions at sub-optimal temperatures.
Notably, growth rates as high as 100 nm/min are obtained by optimizing growth temperature and pressure.
Transient responses are an important aspect of metabolic regulation (see, e.g., [1], [3], [10]), but it is also hypothesized, and in some cases known, that microorganisms excel at optimizing their growth rate in the steady state [2], [11].
To determine the effect of genetic perturbation, all reactions associated with each gene in the iAK692 model were individually removed while still optimizing the growth rate.
However, it is expected that in reality most organisms will naturally choose for optimizing their growth rate, which then results in a marginal improvement of H2 yields.
At each time interval the flux distribution, v, which optimizes the growth rate μ is calculated by solving the optimization problem described in Equations 1, 2, 3 and 6.
The proteins are replenished at the cost of slower growth, and evolution will optimize the growth rate over a set of environmental conditions by tuning the regulation of the protein production rates.
In this study, we always optimize for growth rate.
Mathematically, this represents a degree of uncertainty in the hypothesis that metabolism optimizes only growth rate.
