• Journal of Microbiology and Biotechnology
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• v.26 no.7
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• pp.1182-1189
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• 2016

Lactobacillus brevis ATCC 14869 exhibited a carbon catabolite derepressed phenotype that has ability to consume fermentable sugars simultaneously with glucose. To evaluate this unusual phenotype under harsh conditions during fermentation, the effects of lactic acid and hydrogen ion concentrations on L. brevis ATCC 14869 were examined. Kinetic equations describing the relationship between specific cell growth rate and lactic acid or hydrogen ion concentration were deduced empirically. The change of substrate utilization and product formation according to lactic acid and hydrogen ion concentration in the media were quantitatively described. Although the simultaneous utilization has been observed regardless of hydrogen ion or lactic acid concentration, the preference of substrates and the formation of two-carbon products were changed significantly. In particular, acetic acid present in the medium as sodium acetate was consumed by L. brevis ATCC 14869 under extreme pH of both acid and alkaline conditions.

• Korean Journal of Microbiology
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• v.30 no.6
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• pp.519-523
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• 1992

The glucoamylase of Candida tsuubaensis was purified to homogeneity form culture filtrate by means of ultrafiltration, Sephacryl S-200 gel filtration and Sp-Sephadex C-50 chromatography. The purified enzyme was a glycoprotein with a molecular mass of approximately 50 kDa, which was a monomeric protein. Km values were 5.8 mg/ml for soluble starch and 0.04 mM for maltose. Glucoamylase also released only glucose from both pullulan and isomaltose. The analysis of amino acid composition revealed that the enzyme contained a high content of acidic and polar amino acids. In addition, Western blotting analysis indicates that C. tsukubaensis glucoamylase is resistant to glucose repression.

• KSBB Journal
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• v.10 no.4
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• pp.455-460
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• 1995

Specific growth rate was controlled for the repression of acetic acid formation in the fed-batch fermentation of recombinant Escherichia coli. With controlled specific growth rate, we studied the effect of the specific growth rate on cell growth, glucose consumption, acetic acid formation, and the expression of recombinant protein (${\beta}$-lactamase). High specific growth rate caused the accumulation of glucose and acetic acid, and lowered the production of recombinant protein. However, the addition of methionine recovered the gene expression by alleviating the negative effect of acetic acid at high specific growth rate.

• KSBB Journal
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• v.13 no.3
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• pp.325-330
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• 1998

The methylotrophic yeast, Pichia pastoris, is known to be a potential host to offer many advantages for production of recombinant proteins. Fermentation parameters were optimized to enhance the heterologous ${\beta}$-galactosidase productivity with P. pastoris. Optimum concentration of methanol, used as inducer, was observed to be 8 g/L and the extent of repression of AOX1 promoter by glycerol was lower than by glucose. The degradation of the gene product ${\beta}$-galactosidase by protease was inhibited as the pH increased from 5 to 8 and the yeast extract(1%) as nitrogen source increased expression level 4 times higher compared to yeast nitrogen base(1%) as nitrogen source increased expression level 4 times higher compared to yeast nitrogen base(1%). Induction method, in which methanol is just added to fermentation medium without centrifugation, was found to be as much effective as the one with centrifugation.

• Journal of Microbiology and Biotechnology
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• v.9 no.5
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• pp.568-571
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• 1999

Aspergillus oryzae U1521, which was a genetically engineered strain, produced 1,000,600 U per g . glucose of extracellular alkaline protease within 72 h in a submerged fermentation. However, the alkaline protease was not detected during the first 24 h. Northern blot analysis indicated that the enzyme synthesis was repressed at the transcriptional level during the lag period. Both catabolite repression and pH of the growth medium significantly affected the enzyme production. Use of this enzyme as a silver recovery agent from used X-ray film was confirmed by experiments in the shake-flask scale.

• Journal of Microbiology
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• v.42 no.4
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• pp.319-327
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• 2004

An additional amylase, besides the typical $\alpha-amylase,$ was detected for the first time in the cytoplasm of B. subtilis SUH4-2, an isolate from Korean soil. The corresponding gene (bbmA) encoded a malto­genic amylase (MAase) and its sequence was almost identical to the yvdF gene of B. subtilis 168, whose function was unknown. Southern blot analysis using bbmA as the probe indicated that this gene was ubiquitous among various B. subtilis strains. In an effort to understand the physiological function of the bbmA gene in B. subtilis, the expression pattern of the gene was monitored by measuring the $\beta-galactosidase$ activity produced from the bbmA promoter fused to the amino terminus of the lacZ struc­tural gene, which was then integrated into the amyE locus on the B. subtilis 168 chromosome. The pro­moter was induced during the mid-log phase and fully expressed at the early stationary phase in defined media containing $\beta--cyclodextrin\;(\beta-CD),$ maltose, or starch. On the other hand, it was kept repressed in the presence of glucose, fructose, sucrose, or glycerol, suggesting that catabolite repression might be involved in the expression of the gene. Production of the $\beta-CD$ hydrolyzing activity was impaired by the spo0A mutation in B. subtilis 168, indicating the involvement of an additional regu­latory system exerting control on the promoter. Inactivation of yvdF resulted in a significant decrease of the $\beta-CD$ hydrolyzing activity, if not all. This result implied the presence of an additional enzyme(s) that is capable of hydrolyzing $\beta-CD$ in B. subtilis 168. Based on the results, MAase encoded by bbmA is likely to be involved in maltose and $\beta-CD$ utilization when other sugars, which are readily usable as an energy source, are not available during the stationary phase.

• Journal of Microbiology and Biotechnology
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• v.9 no.2
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• pp.201-205
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• 1999

The effects of growth temperature and a carbon source on the expression of $\beta$-galactosidase gene of Lactococcus lactis ssp. lactis ATCC 7962 (L. lactis 7962) were investigated. At $25^{\circ}C$, L. lactis 7962 had a higher $\beta$-galactosidase activity than cells grown at $30^{\circ}C$ or $37^{\circ}C$, although cells grew most quickly at $37^{\circ}C$ The highest $\beta$-galactosidase activity was observed in cells grown in M17 with lactose (l %) followed by cells grown in a galactose (1 %) medium. L. lactis 7962 exhibited the minimum $\beta$-galactosidase activity in glucose media, indicating catabolite repression. When the cellular levels of $\beta$-galactosidase mRNA were examined using slot blot hybridization, no significant differences were observed between cells grown at $25^{\circ}C$ and cells at $30^{\circ}C$ or $37^{\circ}C$ in the same media. This suggests that the quantity of $\beta$-galactosidase mRNA may not be the reason for the higher $\beta$-galactosidase activities of L. lactis 7962 at $25^{\circ}C$ The level of ccpA (Catabolite Control Protein) transcript remained almost constant during the exponential growth phase irrespective of a carbon sourse.

• Microbiology and Biotechnology Letters
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• v.29 no.3
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• pp.176-180
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• 2001

In plant tissues intercellular cementing portion called as middle lamella consists of high proportion of protopectin that is water insoluble form of pectin on their backbone Protopectinase (PPase) a heterogeneous group of enzymes that hydrolyze or dissolve the insoluble protopectin in plant tissues by restricted depolymerization liberates water solu- ble pectin with the resultant separation of plant tissues that have been protected against environmental shock by rigid cel wall . Bacillus subtilis EKll was most effective for PPase Production For increasing of PPase productivity effects of glucose concentrations, pHs and aeration rates were studied in batch culture The most proper concentra- tion of glucose pH and air condition for PPase Production were 1% 8.0 and lvvm respectively In these condi- tion PPase productivity was $84,364 UL^{-1}$ $h^{-1}$ and increased about 15.6 times than flask fermentation.

• Current Research on Agriculture and Life Sciences
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• v.5
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• pp.68-74
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• 1987

The growth of A calcoaceticus C10 in CL medium was not increased by the addition of 0.5% E-capralactone or succinate, but increased by 0.2% adipate, xylose or even glucose which was not metabolized as a carbon source. The addition of 0.2% glucose after culture in CL medium for 6 hours increased the growth of A. colcoaceticus C10 twice as much as that in CL medium after culture for further 10 hours. Biosynthesis of cyclohexanol dehydrogenase in A. calcoaceticus C10 was not repressed by ${\varepsilon}$-caprolactone, succinate, xylose and glucose, but repressed by adipate which is endproduct of cyclohexanol metabolism. The induction of dehydrogenase by cyc1ohexanol in CL medium was not repressed completely by 0.1% adipate, but repressed almost completely by 0.2% adipate in A. calcoaceticus C10.

• Applied Biological Chemistry
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• v.39 no.6
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• pp.430-436
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• 1996

The induction by xylose and repression by glucose of xylose isomerase(XI) were investigated to elucidate the regulation for production of XI in Escherichia coli. Regulation for expression of xyIA gene which codes XI is under control of xylR which is a regulatory gene for xylose catabolism. When xyIR gene was resided in chromosome, the inductions of XI by the addition of 0.4% xylose were increased to 1.9 and 1.7-fold in case of locating on multicopy(pEX202/DH77) and low copy Plasmid(pEX102/DH77), respectively, as compared with that of xylA gene which was resided in chromosome(JM109). xyIR gene product derived from xyIR gene on chromosome might react to xylA gene on the plasmid as same as xylA gene on chromosome. In JM109 and xylA transformant; pEX202/DH77 and pEX102/DH77, the inductions of XI were completely repressed by the addition of 0.2% glucose and these catabolite repressions were derepressed by the addition of 1 mM cAMP In comparison with the addition of 0.4% xylose only for the induction XI was inductively produced 1.7 to 2-fold with the addition of xylose plus 1 mM cAMP in DM minimal media. pEX13/TP2010, xylA transformant of the deficient mutant($xyl^-,\;cya^-$; TP2010) of XI and cAMP production, did not induce XI by the addition of xylose only but induced in case of simultaneous addition of xylose and cAMP. These results show that cAMP and xylose are the indispensable effectors for the induction and derepression of Xl in E. coli.