DETERMINATION OF GROWTH OF ANAEROBIC FUNGI ON SOLUBLE AND CELLULOSIC SUBSTRATES USING A PRESSURE TRANSDUCER

A pressure transducer was used to determine the accumulation of fermen tation gases during growth of Neocallimastix hurleyensis and Caecomyce s communis on soluble (glucose) and particulate (cellulose and wheat s traw) carbon sources. The anaerobic fungi were grown in submerged batc h culture in gas-tight bottles using conventional anaerobic techniques . As the fermentation progressed, fermentation gases accumulated in th e headspace of culture bottles causing an increase in the head-space g as pressure, Gas was measured and released using a pressure transducer connected to a digital readout voltmeter and gas-tight syringe assemb ly. By repeating this gas measurement-release procedure at regular int ervals during the fermentation, and summation of the calculated (regre ssion corrected) gas volumes, gas accumulation profiles were construct ed. For cultures grown on glucose, this technique enabled the growth o f anaerobic fungi to be evaluated without destructive sampling of the fungal culture. The resultant gas accumulation profiles were related t o glucose loss and biomass accumulation and could be used to determine specific growth rates, doubling times and fermentation gas yields. Fo r cultures grown on cellulose and wheat straw, measurement of gas accu mulation enabled growth phases and the course of the fermentation to b e easily monitored. The results obtained establish the pressure transd ucer as an instrument for rapid, precise and reproducible determinatio n of the growth of anaerobic fungi on soluble and particulate substrat es.