ESTIMATION OF THE KINETIC CONSTANTS AND ELUCIDATION OF TRENDS IN GROWTH AND ERYTHROMYCIN PRODUCTION IN BATCH AND CONTINUOUS CULTURES OF SACCHAROPOLYSPORA-ERYTHRAEA USING CURVE-FITTING TECHNIQUES

The kinetics of erythromycin production were dependent on the identity of the growth rate-limiting nutrient during batch cultures of Sacchar opolyspora erythraea. Semilogarithmic linear regression provided a sin gle estimate of growth rate during the exponential phase, but partial cubic spline curve fit derivatives provided time-dependent specific gr owth and production rate profiles. Non-growth-linked product formation was observed when the medium was glucose- or phosphate-limited. Howev er, growth-linked product formation was observed in a nitrate-limited medium. The kinetics observed in nitrate-limited chemostat culture pro vided evidence that Saccharopolyspora erythraea may be subject to nonc ompetitive inhibition by a growth-linked product under these condition s. A mathematical model was used to test this theory. The model simula tion fitted the observed data very closely and was used to calculate e stimates of the kinetic parameters involved: Yp/x[erythromycin/biomass ] = 1.98 x 10(-3); Yp/s[erythromycin/glucose] = 1.85 x 10(-3); k(i) = 1.56 mg l-1; k(s[glucose]) = 1.5 x 10(-2) mg ml-1; mu(max(chemostat)) = 0.066 h-1