Journals / Turkish Journal of Engineering and Environmental Sciences / 1999 / Cilt: 23 - Sayı: 2
Production of Microbial Rennin in a Continuous System Fermenter and Modelling of the Activity
- Pages
- 83–91
- DOI
- —
Abstract
In this work microbial production of rennin, a milk clotting enzyme, from a commericial strain of Mucor miehei (NRRL 3420, USDA) has been investigated in a continuous fermenter. The spherical biofilm type growth of the culture has been accomplished in the fermenter and the effects of operational parameters; medium pH, mixing rate (K.H.), dilution rate (D) and feed D-glucose concentration (S_{gf) on milk clotting activity (S.P.A.) have been elaborated. For a fermenter sample containing 1.24 IU/mL S.P.A., optimum production parameters at 37 °C have been determined as K.H.=400 rpm, D=0.125 day^{-1 and S_{gf=7.5 g/L without pH control. Under these conditions, the fermenter operated 575 hours continuously producing 10230 IU S.P.A. in total. In the fermenter sample, R factor and specific S.P.A. were deteremined as 1.55x10^{-3 S.P.A/P.A. and 5.28 IU/mg protein, respectively, denoting competitive activity of a commercial rennet after concentration. In model simulation studies of the results, maximum S.P.A. obtained has been succesfully represented with a multiple-linear function expressed in terms of fermentation medium pH, D-glucose and dissolved oxygen concentrations and dilution rate. Model simulations also showed that enzyme production rate was solely controlled by fermentation medium characteristics rather than operational fermenter parameters.
Özet
In this work microbial production of rennin, a milk clotting enzyme, from a commericial strain of Mucor miehei (NRRL 3420, USDA) has been investigated in a continuous fermenter. The spherical biofilm type growth of the culture has been accomplished in the fermenter and the effects of operational parameters; medium pH, mixing rate (K.H.), dilution rate (D) and feed D-glucose concentration (S_{gf) on milk clotting activity (S.P.A.) have been elaborated. For a fermenter sample containing 1.24 IU/mL S.P.A., optimum production parameters at 37 °C have been determined as K.H.=400 rpm, D=0.125 day^{-1 and S_{gf=7.5 g/L without pH control. Under these conditions, the fermenter operated 575 hours continuously producing 10230 IU S.P.A. in total. In the fermenter sample, R factor and specific S.P.A. were deteremined as 1.55x10^{-3 S.P.A/P.A. and 5.28 IU/mg protein, respectively, denoting competitive activity of a commercial rennet after concentration. In model simulation studies of the results, maximum S.P.A. obtained has been succesfully represented with a multiple-linear function expressed in terms of fermentation medium pH, D-glucose and dissolved oxygen concentrations and dilution rate. Model simulations also showed that enzyme production rate was solely controlled by fermentation medium characteristics rather than operational fermenter parameters.