INFLUENCE OF pH, TEMPERATURE AND DISSOLVED OXYGEN CONCENTRATION ON THE PRODUCTION OF GLUCOSE 6-PHOSPHATE DEHYDROGENASE AND INVERTASE BY Saccharomyces cerevisiae

Abstract

The effect of pH (from 4.0 to 5.0), temperature (T) (from 30 oC to 40 oC) and dissolved oxygen concentration (DO) (from 0.2 to 6.0 mg O2/L) on glucose 6-phosphate dehydrogenase (G6PDH) (EC 1.1.1.49) and Invertase (EC 3.2.1.26) formation by S. cerevisiae were studied. The best culture conditions for G6PDH and Invertase formation were: 2.55 L culture medium (yeast extract, 3.0 g/L; 5peptone, 5.0 g/L; glucose, 2.0 g/L; sucrose, 15.0 g/L; Na2HPO4.12 H2O, 2.4 g/L; (NH4)2SO4, 5.1 g/L and MgSO4. 7H2O, 0.075 g/L); 0.45 L inoculum (0.70 g dry cell/L); pH = 4.5; T = 35 oC and DO = 4.0 mg/L. G6PDH was highly sensitive to pH, T and DO variation. The increase in G6PDH production was about three times when the DO ranged from 0.2 to 4.0 mg O2/L. Moreover, by shifting pH from 5.0 to 4.5 and temperature from 30 oC to 35 oC, G6PDH formation increased by 57% and 70%, respectively. Invertase activity (IA) of whole cells decreased at least 50% at extremes values of DO (2.0 and 6.0 mg O2/L) and pH (4.0 and 5.0). Furthermore, IA oscillated during the fermentation due to the glucose repression/derepression mechanis

Glucose‐6‐phosphate dehydrogenase partitioning in two‐phase aqueous mixed (nonionic/cationic) micellar systems

“…This enzyme is also of great interest as an analytical reagent, being used in various quantitative assays, including the measurement of creatin-kinase activity for diagnosis of heart and skeletal-muscle diseases, the measurement of hexose concentrations, and as a marker for enzyme immunoassays (Lojudice et al, 2001). The use of G6PD for measuring glucose in the presence of fructose constitutes an important tool for the detection of illegal sugar addition in the final products of the wine and fruit juice industries (Abrahão-Neto et al, 1997). This enzyme can also be used to identify and quantify glucose released by starch hydrolysis in fruit preparations, even in the presence of fruit pieces, colored compounds, high concentrations of sucrose, and other kinds of polyssacharides (Chatel et al, 1996).…”

Effect of cultivation conditions on glucose-6-phosphate dehydrogenase production by genetically modified Saccharomyces cerevisiae

“…The three evaluated variables were: pH value, inoculum concentration and initial glucose concentration. The pH values were chosen based on previous results reported by Abrahão-Neto et al (1997), while the inoculum concentration (initial yeast concentration) and initial glucose concentration were chosen based on previous results referred by Silva et al (2002). To maintain constant the C/N ratio (C/N = 7), the nitrogen concentration (from YNB and aminoacids) in the cultivation medium was changed as a function of carbon source concentration (initial glucose concentration).…”

“…This enzyme is used as an analytical reagent for the measurement of hexokinase and creatin-kinase activities, ATP, as well as in enzyme immunoassays, either ELISA (enzyme-linked immunosorbent assay) or EMIT (enzyme multiplied immunotechnique), for diagnostic purposes (Bergmeyer, 1984;Ivison et al, 2000). The use of G6PD for measuring glucose in the presence of fructose constitutes an important tool for the detection of illegal sugar addition in the final products of the wine and fruit juice industries (Abrahão-Neto et al, 1997). This enzyme can also be used, efficiently and accurately, to identify and quantify glucose released by starch hydrolysis in fruit preparations, even in the presence of fruit pieces, pigments, high concentrations of sucrose and other kinds of polysaccharides (Chatel et al, 1996).…”

Produção de glicose-6-fosfato desidrogenase de "Saccharomyces cerevisiae" geneticamente modificada através de processo descontínuo alimentado

“…Esses kits podem ser utilizados para medidas de teores de glicose, frutose, manose, ATP (BOROSS et al,1987; AGUERO,1998) e de atividade enzimática de hexoquinase e creatino-quinase (ABRAHÃO- NETO et al, 1997). Usando a G6PDH, é possível determinar glicose na presença de outros sacarídeos, como a frutose (WHYTAKER,1991;CHATEL et al 1996).…”

“…Essa enzima pode ser utilizada em kits para medidas de teores de glicose, frutose, manose, ATP (BOROSS et al,1987;AGUERO,1998) e de atividade enzimática de hexoquinase e creatino-quinase (ABRAHÃO-NETO et al, 1997).…”