Improvement of cloned α‐amylase gene expression in fed‐batch culture of recombinant Saccharomyces cerevisiae by regulating both glucose and ethanol concentrations using a fuzzy controller

Abstract

The effect of ethanol concentration on cloned gene expression in recombinant Saccharomyces cerevisiae strain 20B-12 containing one of two plasmids, pNA3 and pNA7, was investigated in batch cultures. Plasmids pNA3 and pNA7 contain the alpha-amylase gene under the control of the SUC2 or PGK promoter, respectively. When the ethanol concentration was controlled at 2 to 5 g/L, the gene expressions were two times higher than those at 20 g/L ethanol. The increase the gene expression by maintaining both the ethanol and glucose concentrations at low levels, a fuzzy controller was developed. The concentrations of glucose and ethanol were controlled simultaneously at 0.15 and 2 g/L, respectively, in the production phase using the fuzzy controller in fed-batch culture. The synthesis of alpha-amylase was induced by the low glucose concentration and maintained at a high level of activity by regulating the ethanol concentration at 2 g/L. The secretory alpha-amylase was induced by the low glucose concentration and maintained at a high level of activity by regulating the ethanol concentration at 2 g/L. The secretory alpha-amylase activities of cells harboring plasmids pNA3 and pNA7 in fed-batch culture were 175 and 395 U/mL, and their maximal specific activities 7.7 and 12.4 U/mg dry cells, respectively. These values are two to three times higher in activity and three to four times higher in specific activity than those obtained when glucose only was controlled.

A fuzzy logic algorithm for identification of the harvesting threshold during PGA production by Bacillus megaterium

“…Yamada et al (1991) used fuzzy control during the fed-batch fermentation for production of the coenzyme Q 10 . Shiba et al (1994) employed a fuzzy system to control the concentrations of glucose and ethanol in the medium for Saccharomyces cerevisiae cultivations. The objective was to improve α-amylase production in a bioreactor operated in fed-batch mode.…”

Intelligent Models of the Quantitative Behavior of Microbial Systems

“…Therefore, a constant rate of glucose feed results in oscillating concentrations of glucose, DO, and ethanol in the culture broth (Patnaik 2003a;Shi and Shimizu 1992). Shi and Shimizu (1992), Park et al (1993) and Shiba et al (1994) proposed fuzzy inference rules to control the feed rate of glucose so as to enhance ethanol production beyond what was possible through mechanistic models and conventional optimization.…”

Airlift-driven fibrous-bed bioreactor for continuous production of glucoamylase using immobilized recombinant yeast cells

“…Furthermore, by utilizing yeast proteins secretion systems, foreign peptides can be secreted to the external medium. In this respect, by utilizing yeast secretion systems, such as ␣-factor signal peptide, attempts were made to produce several recombinant proteins (Kilonzo et al, 2008;Gorgens et al, 2001;Bannister and Wittrup, 2000;Shiba et al, 1994;Vainio et al, 1994;Chau et al, 2000;Chen et al, 2006;Ekino et al, 2002).…”