ACCURATE DETERMINATION OF PROCESS VARIABLES IN A SOLID-STATE FERMENTATION SYSTEM

The solid-stare fermentation (SSF) method described enabled accurate d etermination of variables related to biological activity. Growth, resp iratory activity and production of carboxymethyl-cellulose-hydrolysing enzyme (CMC-ase) activity by Trichoderma reesei QM9414 on wheat bran was used as a model SSF. The standard deviation (s) of measured substr ate weight loss and glucosamine content, and the overall standard devi ation of oxygen consumption rate (OCR) and carbon-dioxide production r ate (CPR) after 72 h of fermentation were less than 7% of the mean mea sured values. A statistical method to estimate the standard deviation of time-dependent data is presented. A closed carbon balance could be set up with the results of the measurements of CPR, elemental composti on and chemical composition, indicating the reliability of the methods used. Measurements of CMC-ase activity were less accurate due to inte raction between substrate and product. The measurement of the ATP leve l was also less accurate. Copyright (C) 1996 Elsevier Science