, Volume 43, Issue 1, pp 42-46

Agar gel immobilization ofBacillus brevis cells for production of thermostable α-amylase

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Growing cells of a thermophilic strain ofBacillus brevis, producer of thermostable α-amylase, were immobilized by entrapment in agar gel. Optimum immobilization conditions for effective α-amylase production in batch fermentations were established (gel concentration 3%, initial biomass concentration in the gel 0.8% (W/V), and preculture age—late exponential phase). The dynamics of α-amylase synthesis by the biocatalysts obtained under the optimal conditions was compared with that of free cells and the operational stability of the biocatalysts was studied in semicontinuous cultivation experiments. Maximum α-amylase yields (252% of the control) were achieved after the second cycle of cultivation. Scanning electron microscopy was used to characterize the bacteria entrapped in agar gel.