title: Effect of growth rate on alpha-amylase production by Streptomyces sp. IMD 2679.
abstract: The alpha-amylase of Streptomyces sp. IMD 2679 was subject to catabolite repression. Four different growth rates were achieved when the organism was grown at 40 degrees C and 55 degrees C in the presence and absence of cobalt, with an inverse relationship between alpha-amylase production and growth rate. Highest alpha-amylase yields (520 units/ml) were obtained at the lowest growth rate (0.062 h-1), at 40 degrees C in the absence of cobalt, while at the highest growth rate (0.35 h-1), at 55 degrees C in the presence of cobalt, alpha-amylase production was decreased to 150 units/ml. As growth rate increased, the rate of specific utilisation of the carbon source maltose also increased, from 46 to 123 micrograms maltose (mg biomass)-1 h-1. The pattern and levels of alpha-glucosidase (the enzyme degrading maltose) detected intracellularly in each case, indicate that growth rate effectively controls the rate of feeding of glucose to the cell, and thus catabolite repression.
authors.affiliation: Department of Industrial Microbiology, University College Dublin, Belfield, Ireland.
authors.forename: H E
authors.initials: HE
authors.lastname: Mc Mahon
authors.forename: C T
authors.initials: CT
authors.lastname: Kelly
authors.forename: W M
authors.initials: WM
authors.lastname: Fogarty
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D008320:Maltose / Q000378:metabolism; D013302:Streptomyces / Q000201:enzymology* / Q000254:growth & development; D000516:alpha-Amylases / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D008320:Maltose; D000516:alpha-Amylases