CULTIVATION OF THERMOANAEROBIUM-BROCKII IN CONTINUOUS-CULTURE WITH COMPLETE CELL RECYCLING

The growth behaviour of the thermophilic anaerobic bacterium Thermoana erobium brockii for the production of its intracellular secondary alco hol dehydrogenase (sADH) has been studied in batch cultures as well as in continuous cultivation with complete cell recycling. In batch cult ure the maximum specific growth rate, mu(max), was 0.5 h(-1), resultin g in a cell density of 1.2 g l(-1) and an sADH activity of 1.3 units m l(-1). Higher glucose concentrations resulted in a decrease in mu(max) , enzyme productivity as well as biomass yield although an increase in total biomass was achieved. To improve cell density and productivity, continuous culture with complete cell recycling was used, resulting i n an increase in cell density by 5 times and in productivity of the sA DH by 3 times in comparison to those obtained in batch culture.