Continuous Culture to Produce Recombinant β-Galactosidase in Bacillus subtilis

Abstract

A chromosomal-recombinant bacterial strain, Bacillus subtilis BIBTIO, was used to study the J3-galactosidase production in continuous culture. The integrated genes consisted of the Escherichia coli lacZ gene controlled by the aprE promoter and the Staphylococcus aureus chloramphenicol resistance gene. The specific rate of f3-galactosidase production was maximal at a specific growth rate of approximately 0.5 hoi. A dilution rate of 0.4 h-I (in which less than 2% spores were found) was chosen to carry out extended production experiments. After 50 mean generation times, J3-galactosidase production remained constant, indicating the high stability of this system. The f3-galactosidase productivity in continuous culture, at a dilution rate of 0.4 h-I , was 3.2 fold higher than that of batch cultures.