Effect of pH, aeration and sucrose feeding on the invertase activity of intact S. cerevisiae cells grown in sugarcane blackstrap molasses.
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 O2 L-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 attaining S. cerevisiae cells suitable for invertase production were: temperature = 30 degrees C; pH = 5.0; DO = 3.3 mg O2 L-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.
Vitolo
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Faculdade de Ciências Farmacêuticas, University of São Paulo, Brazil.
Duranti
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MA
Pellegrim
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MB
D003470:Culture Media / Q000737:chemistry; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000096:biosynthesis* / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D008965:Molasses; D010100:Oxygen / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D013395:Sucrose / Q000494:pharmacology*; D043324:beta-Fructofuranosidase
D003470:Culture Media; D013395:Sucrose; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase; D005947:Glucose; D010100:Oxygen