For the preparation of single cell protein from cellulose with Strep-tomyces No. 107
a simplified reaction model has been established based on the mathematical model developed by Armiger-Humphrey. The model consisted of 4 ordinary differential equations including 9 parameters to be estimated. Using the VAX-11/780 computer and a STYR/OPT optimization program developed in this Institute the parameters included in the model were estimated by optimization and the experimental results were simulated by the model satisfactorily. The value of the 9 parameters optimized were reasonable and the simulation of experimental results was successful.