Effect of growth rate on alpha-amylase production by Streptomyces sp. IMD 2679.
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.
Mc Mahon
H E
HE
Department of Industrial Microbiology, University College Dublin, Belfield, Ireland.
Kelly
C T
CT
Fogarty
W M
WM
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
D001426:Bacterial Proteins; D003470:Culture Media; D008320:Maltose; D000516:alpha-Amylases