Entropy balances of microbial product formation

Considering the approach of Bermudez and Wagensberg (1986) devoted to the entropy balance of growing microorganisms some equations were developed which describe particularly the entropy balance of microbial product formation. The formula allows to determine the coefficients of resistance R(mn) and of coupling L(mn) according to rates of growth, product formation, maintenance metabolism and heat evolution assuming a linear relationship between thermodynamic fluxes and forces. In order to check the usefulness of the derived model appropriate experimental data of two microbial batch processes concerning production of L-lysine and the antibiotic nourseothricine were taken into account. The results showed similar courses of entropy balances despite different pathways of product formation which were characterized by an overshoot of entropy production at the beginning of biosynthesis of the primary and secondary metabolite. This fact was interpreted as a more general phenomenon for microorganisms under inbalanced nutritional conditions.