title: Continuous Production of Thermostable beta-Amylase with Clostridium thermosulfurogenes: Effect of Culture Conditions and Metabolite Levels on Enzyme Synthesis and Activity.
abstract: A beta-amylase-overproducing mutant of Clostridium thermosulfurogenes was grown in continuous culture on soluble starch to produce thermostable beta-amylase. Enzyme productivity was reasonably stable over periods of weeks to months. The pH and temperature optima for beta-amylase production were pH 6.0 and 60 degrees C, respectively. Enzyme concentration was maximized by increasing biomass concentration by using high substrate concentrations and by maintaining a low growth rate. beta-Amylase concentration reached 90 U ml at a dilution rate of 0.07 h in a 3% starch medium. A further increase in enzyme activity levels was limited by acetic acid inhibition of growth and low beta-amylase productivity at low growth rates.
authors.affiliation: Michigan Biotechnology Institute, 3900 Collins Road, Lansing, Michigan 48909, and Departments of Biochemistry and Microbiology, Michigan State University, East Lansing, Michigan 48824.
authors.forename: A
authors.initials: A
authors.lastname: Nipkow
authors.forename: G J
authors.initials: GJ
authors.lastname: Shen
authors.forename: J G
authors.initials: JG
authors.lastname: Zeikus