Cultivation of Thermoanaerobium brockii in continuous culture with complete cell recycling

Abstract

The growth behaviour of the thermophilic anaerobic bacterium Thermoanaerobium brockii for the production of its intracellular secondary alcohol dehydrogenase (sADH) has been studied in batch cultures as well as in continuous cultivation with complete cell recycling. In batch culture the maximum specific growth rate, μ max , was 0.5 h -1 , resulting in a cell density of 1.2 g l -1 and an sADH activity of 1.3 units ml -1 . Higher glucose concentrations resulted in a decrease in μ 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 in an increase in cell density by 5 times and in productivity of the sADH by 3 times in comparison to those obtained in batch culture.