Use of a novel turbidimeter to monitor microbial growth and control glucose concentration

A turbidimeter (suspended solid concentration analyser: SSCA) which can measure directly the turbidity of culture broth has been developed. The SSCA was used to monitor baker's yeast and Escherichia coli fermentations. Although the medium conditions changed during the fermentations, the optical densities evaluated from the measurement of SSCA and predetermined calibration curves coincided well with those determined spectrophotometrically. Since SSCA can monitor microbial growth, it was applied to the control of glucose concentration in fed-batch baker's yeast cultures by assuming a constant growth yield. Glucose concentration in the medium could be maintained between 0.2 and 0.3 g dm−3, and ethanol concentration was less than 4 g dm−3.