• KSBB Journal
• /
• v.10 no.4
• /
• pp.370-373
• /
• 1995

The major by-products in ethanol fermentation by Saccharomyces cerevisiae were glycerol, acetaldehyde, acetic acid, lactic acid, and formic acid. The effects of these by-products on the cell growth and ethanol production were studied. By adding acetaldehyde or acetic acid in the fermentation broth, the cell growth decreased while the ethanol production increased. But glycerol and lactic acid had nearly no effects on the cell growth and the ethanol production. Acetic acid and acetaldehyde inhibited the cell growth by diminishing the growth rate as well as by prolonging the lag phase. The ethanol yield increased with the elevation of concentrations of acetic acid and acetaldehyde in the fermentation broth. The maximum ethanol yield was obtained for $3g/\ell$ acetic acid and $2g/\ell$ acetaldehyde, respectively.

• Microbiology and Biotechnology Letters
• /
• v.35 no.1
• /
• pp.36-40
• /
• 2007

Redox signaling is one of way to regulate growth and death of cell in response to change of redox of proteins. To search whether translation is regulated by redox, we attempted in vitro translation assay under condition with or without DTT. Interestingly in vitro translation activity was increased up to 40% In the presence of dithiothreitol (DTT). Then we checked whether this positive effect by DTT was further accelerated by addition of thioredoxin (Trx). When a Trx purified from Saccharomyces cerevisiae was added to the in vitro translation extract, we observed a dose-dependent increase in translational activity. These results suggest the possibility of translation factors being redox-regulated via Trx in vivo.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.11 no.4
• /
• pp.114-119
• /
• 2003

The fermentative conversion of food wastes into probiotic feed was investigated by seeding of mixed inoculum of Lactobacillus acidophilus and Saccharomyces cerevisiae. After grinding finely, optimal fermentation conditions for aeration was investigated at $30^{\circ}C$, The viable cell count of lactic acid bacteria and yeast during fermentation were monitored by controlling aeration rate at each different aeration degree of 0v.v.m 0rpm, 0.25v.v.m 100rpm, 0.5v.v.m 200rpm, and 1v.v.m 500rpm respectively. The most active growth of the yeast was shown at 0.5v.v.m 200rpm as $4.5{\times}10^9CFU/m{\ell}$. By controlling aeration rate, the pH of the probiotics feed could be controlled between 4-5 for the enhancement of preservation characteristics and acceptability for cattle feeding.

• Applied Biological Chemistry
• /
• v.34 no.1
• /
• pp.67-74
• /
• 1991

In order to improve the productivity of ethanol by sugar-alcohol-tolerant Saccharomyces cerevisiae D1, the effect of addition of $Ca^{2+}$ on the alcohol fermentation was investigated. The addition of $Ca^{2+}$led to both the improvement of ethanol productivity and the increase of viable cell concentration. The optimal concentration of $Ca^{2+}$ was 0.8 mM. The higher was initial concentration of glucose, the greater effect of $Ca^{2+}$ was observed. Ethanol inhibition of growth, specific death rate in lethal concentration of ethanol, and extracellular final pH decreased by the addition of $Ca^{2+}$. The effect of $Ca^{2+}$ supplementation was explained by the increase of its ethanol tolerance.

• The Korean Journal of Mycology
• /
• v.23 no.2 s.73
• /
• pp.129-138
• /
• 1995

DNA fragment being able to restore in vitro activity of ${\beta}-1,3-glucan$ synthase was cloned by transformation of the Saccharomyces cerevisiae LP353 mutant strain with genomic library constructed in the YCp50. For the selection of transformants which showed no detectable phenotype linked to recovery of the defect in ${\beta}-1,3-glucan$ synthase activity, the colony autoradiography was succesfully applied. The restriction map of the cloned DNA fragment, which is 8.5-kb in length, was constructed. Both the YEplac195 and the YCp50 carrying the 8.5-kb fragment increased ${\beta}-1,3-glucan$ synthase activity of LP353 by two fold. Neither the YEplac195 nor the YCp50 carrying the 8.5-kb DNA fragment, however, complemented the temperature-dependent osmotic sensitivity which is another distinctive phenotype of LP353. Subcloning experiments indicated that a functional region was located in 4.8-kb BglII-KpnI fragment. The 4.8-kb fragment was also able to increase the level of ${\beta}-1,3-glucan$ content in cell wall as well as the resistance of cells to cell wall lytic enzyme, ${\beta}-1,3-glucanase$. The growth rate of the LP353 with 4.8-kb fragment was almost same as that of wild type strain in liquid medium with 1.2 M sorbitol at nonpermissive temperature. Taken these results together, the 4.8-kb fragment seemed to contain the BGS2 gene for ${\beta}-1,3-glucan$ synthase activity in yeast S. cerevisiae.

• KSBB Journal
• /
• v.10 no.5
• /
• pp.475-481
• /
• 1995

The effect of metallothionein expression on the metal resistance and removal by recombinant Saccharomyces cerevisiae containing the plasmid pJW9 was investigated. The recombinant strain S. cerevisiae BZ-pJ was constructed by transforming the host strain S. cerevisiae BZ3l-1-7Ba with the gene coding for a metal-binding protein, metallothionein. Introduction of the MT gene yielded an increase in the minimum inhibitory concentration (MIC) of copper more than three times compared with the host strain. The minimum inhibitory concentrations of $Cr^{2+}, Znr^{2+} and Pb^{2+}, $ were not different for the two strains. The recombinant yeast grown in a medium containing 8mM CuSO4 was able to remove copper with a capacity of 18.9mg $Cu^{2+}$/g dry cell. In a mixture of copper and zinc, the presence of copper relieved the toxic effects caused by zinc, resulting in an enhancement of the final cell density and the specific growth rate of the recombinant yeast. The capability to remove copper by the recombinant yeast was linearly proportional to the copper concentrations in the medium. The efficiency of copper removal was rather constant regardless of the initial copper concentrations. The specific removal of zinc was dependent on the zinc concentrations in media, though, and such dependence was not so pronounced as the concentration of copper.

• KSBB Journal
• /
• v.7 no.1
• /
• pp.27-31
• /
• 1992

Xylose represents a major component of cellulosic materials. This paper describes patterns of ethanol fermentation by Saccharomyces cerevisiae from xylulose, which is an isomer of xylose. Special emphasis was placed on the effects of xylulose concentration and growth temperature on cell growth and ethanol yield. The maximum specific growth of $0.087 1/hr^{-1}$ was obtained at an initial xylulose concentration of 5 g/1. The ethanol yield was propotional to initial xylulose concentrations. A xylulose concentration of 16 g/l resulted in the maximum ethanol yield of 0.49 g EtOH/g xylulose, which corresponds to 90% of a theoretical value. It is interesting to nota that xylulose metabolism was accelerated by the presence of glucose as a carbon source.

• Microbiology and Biotechnology Letters
• /
• v.26 no.5
• /
• pp.406-412
• /
• 1998

The endoglucanase gene, egl6, of Trichoderma sp. was connected with the yeast ADH1 promoter, and the resultant plasmid, pVT-C4, was introduced into three S. cerevisiae host strains (YNN27, 2805, and SEY2102). Among each 80 transformants, the cell growth and expression level of endoglucanase were compared in test-tube cultivation, and three respective transformants for each host cells showing the highest expression level and cell growth were selected. When three recombinant yeast cells were batchwise cultivated for 48 hr in flask, the total activities of endoglucanase expressed were about 1140 unit/l with 2805/pVT-C4, 1020 unit/l with SEY2102/pVT-C4, and 590 unit/l with YNN27/pVT-C4. Irrespective of host strain, about 80% of the expressed endoglucanase was detected in the extracellular medium. In addition, it was also found that the recombinant enzyme was secreted into the culture medium as two major forms of lightly and heavily glycosylated proteins.

• Applied Biological Chemistry
• /
• v.39 no.1
• /
• pp.1-8
• /
• 1996

A one-stage, continuous-flow bioreactor with both immobilized and suspended cells was used to investigate the roles of lipid supplements in ethanol production by Saccharomyces cerevisiae. The reactor performance and the level of alcohol dehydrogenase(ADH) activities of the suspended cells, grown under various conditions, were measured. When ergosterol and/or oleic acid were added with surfactants to the yeast culture grown under non-aerated conditions, remarkable increases in ethanol production and cell growth was achieved, but specific ADH activities were not affected. Especially, no difference of specific ADH activities of the suspended cells grown under aerated and non-aerated condition was observed. The addition of the surfactant as a supplement also resulted in significant increases in ethanol production, cell growth, and specific ADH activity. When ergosterol and oleic acid were added to the yeast culture exposed to higher ethanol concentration($>40\;g/{\ell}$) level, ethanol production, cell growth, and specific ADH activity were increased, but the addition of surfactant was as effective as at lower ethanol concentration level. The results indicated that lipid supplements were more effective at higher ethanol concentration level than at lower ethanol concentration level during ethanol production. ADH isozyme patterns of the yeast cultures grown under various conditions on starch gel electrophoresis showed only one major band, probably ADH I. The migrating distance of the major isozyme, however, varied slightly according to the culture conditions of the cells. No apparent correlation was found between specific ADH activity and amount of ethanol produced. Cell mass was more important factor for ethanol production than specific ADH activity of the cells.

• Korean Journal of Food Science and Technology
• /
• v.19 no.1
• /
• pp.54-60
• /
• 1987

Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) were tested for their effectiveness in inhibiting the growth of microorganisms. Among the test microorganisms, the growth of three yeasts (Saccharomyces cerevisiae, Kloeckera apiculata, Cryptococcus hungaricus), three bacteria (Bacillus subtilu, Lactobacillus cases, Escherichia colt) and two molds (Aspergillus oryzae. Penicillium sp.) was progressively decreased as concentrations of BHA were increased. A. oyzae was completely inhibited with 100ppm of BHA and a majority of the test microorganisms (S. cerevisiae, K. apiculata. C. hungaricus, B. subtilis, A. oryzae) were completely inhibited by 150 ppm of BHA. The growths of L. casei, E. coli and Penicillium sp. were not affected as much as those of other microorganisms by BHA. Final cell yiedls were becoming lower as the concentration of BHA increased. The growth of C. hungaricus and L. casci was slightly inhibited by BHT. Other microorganisms were not effected by the test concentrations of BHT.