Effect of pH,aeration and sucrose feeding on the invertase activity of intactS. cerevisiae cells grown in sugarcane blackstrap molasses |
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Authors: | M Vitolo M A Duranti M B Pellegrim |
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Affiliation: | (1) Faculdade de Ciências Farmacêuticas, University of São Paulo, PO Box 66083, 05389-970 São Paulo, SP, Brazil |
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Abstract: | S. cerevisiae was grown in a blackstrap molasses containing medium in batch and fed-batch cultures. The following parameters were varied: pH (from 4.0 to 6.5), dissolved oxygen (DO) (from 0 to 5.0 mg O2L–1) and sucrose feeding rate. When glucose concentration (S) was higher than 0.5 g L–1 a reduction in the specific invertase activity of intact cells (v) and an oscillatory behavior of v values during fermentation were observed. Both the invertase reduction and the oscillatory behavior of v values could be related to the glucose inhibitory effect on invertase biosynthesis. The best culture conditions for attainingS. cerevisiae cells suitable for invertase production were: temperature=30°C; pH=5.0; DO=3.3 mg O2L–1; (S)=0.5 g L–1 and sucrose added into the fermenter according to the equations: (V–Vo)=t2/16 or (V–Vo)=(Vf–Vo)·(e0.6t–1)/10.This work was supported by FAPESP |
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Keywords: | molasses invertase activity S. cerevisiae |
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