• Journal of Microbiology and Biotechnology
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• v.21 no.1
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• pp.55-61
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• 2011

Forty yeast strains isolated from soils taken from different locations in Egypt were tested for their P-solubilizing activities on the basis of analyzing the clear zone around colonies growing on a tricalcium phosphate medium after incubation for 5 days at $25^{\circ}C$, denoted as the solubilization index (SI). Nine isolates that exhibited P-solubilization potential with an SI ranging from 1.19 to 2.76 were genetically characterized as five yeasts belonging to the genus Saccharomyces cerevisiae and four non-Saccharomyces, based on a PCR analysis of the ITS1-26S region amplied by SC1/SC2 species-specific primers. The highest P-solubilization efficiency was demonstrated by isolate PSY- 4, which was identified as Saccharomyces cerevisiae by a sequence analysis of the variable D1/D2 domain of the 26S rDNA. The effects of single and mixed inoculations with yeast PSY-4 and Bacillus polymyxa on the P-uptake and growth of corn were tested in a greenhouse experiment using different levels of a phosphorus chemical fertilizer (50, 100, and 200 kg/ha super phosphate 15.5% $P_2O_5$). The results showed that inoculating the corn with yeast PSY-4 or B. polymyxa caused significant increases in the shoot and root dry weights and P-uptake in the shoots and roots. The P-fertilization level also had a significant influence on the shoot and root dry weights and P-uptake in the shoots and roots when increasing the P-level from 50 up to 200 kg/ha. Dual inoculation with yeast strain PSY-4 and B. polymyxa at a P-fertilization level of 200 kg/ha gave higher values for the shoot and root dry weights and P-uptake in the shoots and roots, yet these increases were nonsignificant when compared with dual inoculation with yeast strain PSY-4 and B. polymyxa at a P-fertilization level of 100 kg/ha. The best increases were obtained from dual inoculation with yeast strain PSY-4 and B. polymyxa at a P-fertilization level of 100 kg/ha, which induced the following percentage increases in the shoot and root dry weights, and P-uptake in the shoots and roots; 16.22%, 46.92%, 10.09%, and 31.07%, respectively, when compared with the uninoculated control (fertilized with 100 kg/ha).

• Mycobiology
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• v.42 no.4
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• pp.361-367
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• 2014

Makgeolli, also known as Takju, is a non-filtered traditional Korean alcoholic beverage that contains various floating matter, including yeast cells, which contributes to its high physiological functionality. In the present study, we assessed the levels of ${\beta}$-glucan and glutathione in various yeast strains isolated from traditional Korean Nuruk and selected a ${\beta}$-glucan- and glutathione-rich yeast strain to add value to Makgeolli by enhancing its physiological functionality through increased levels of these compounds. Yeast ${\beta}$-glucan levels ranged from 6.26% to 32.69% (dry basis) and were strongly species-dependent. Dried Saccharomyces cerevisiae isolated from Nuruk contained $25.53{\mu}g/mg$ glutathione, $0.70{\mu}g/mg$ oxidized glutathione, and $11.69{\mu}g/g$ and $47.85{\mu}g/g$ spermidine and L-ornithine monohydrochloride, respectively. To produce functional Makgeolli, a ${\beta}$-glucan- and glutathione-rich yeast strain was selected in a screening analysis. Makgeolli fermented with the selected yeast strain contained higher ${\beta}$-glucan and glutathione levels than commercial Makgeolli. Using the selected yeast strain to produce Makgeolli with high ${\beta}$-glucan and glutathione content may enable the production of functional Makgeolli.

• Journal of Microbiology
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• v.45 no.2
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• pp.128-132
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• 2007

The red yeast Xanthophyllomyces dendrorhous (previously named Phaffia rhodozyma) produces astaxanthin pigment among many carotenoids. The mutant X. dendrorhous G276 was isolated by chemical mutagenesis. The mutant produced about 2.0 mg of carotenoid per g of yeast cell dry weight and 8.0 mg/L of carotenoid after 5 days batch culture with YM media; in comparison, the parent strain produced 0.66 mg/g of yeast cell dry weight and a carotenoid concentration of 4.5 mg/L. We characterized the utilization of carbon sources by the mutant strain and screened various edible plant extracts to enhance the carotenoid production. The addition of Perilla frutescens (final concentration, 5%) or Allium fistulosum extracts (final concentration, 1%) enhanced the pigment production to about 32 mg/L. In a batch fermentor, addition of Perilla frutescens extract reduced the cultivation time by two days compared to control (no extract), which usually required five-day incubation to fully produce astaxanthin. The results suggest that plant extracts such as Perilla frutescens can effectively enhance astaxanthin production.

• Food Science and Preservation
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• v.17 no.2
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• pp.174-181
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• 2010

The yeast strains used for fermentation are known to influence the qualities of wine. We investigated the effects of fermentation using different yeast strains on the properties of wine produced from 'Hayward' kiwifruit (Actinidia deliciosa). The physicochemical characteristics of wine produced using various yeast strains for fermentation were also analyzed. Saccharomyces cerevisiae Gervin No.5 strain (GVN), S. bayanus Lavin strain EC1118 (EC1118), and S. cerevisiae Red star Davis No. 796 (No.796) are commercial dry yeast strains selected for optimization of fermentation. Although the soluble solid contents of samples fermented by all three yeast strains decreased by a similar extent, the levels of alcohol production differed, particularly during the first week of fermentation. Use of the GVN strain resulted in the highest alcohol concentration (13.8%, v/v), whereas fermentation with No.796 and EC1118 strains yielded alcohol contents of 13.0% and 12.5% (both v/v), respectively. Upon sensory evaluation, GVN-fermented wine had a strong taste and bitterness, with high acid and alcohol contents. Wine fermented using No.796 had a chemical profile similar to that of GVN-fermented product, but the taste remained sweet, consistent with the lower alcohol content. EC1118-fermented wine was soft and sweet in taste, high in flavor, and had a low alcohol content. Total phenolic levels and antioxidant activities in wine fermented by EC1118 were significantly higher than in wines prepared using No.796 or GVN. When previously described characteristics were additionally considered, EC1118 was selected as an optimum strain for further study. In conclusion, fermentation of kiwifruit using different yeast strains yielded wines with distinct characteristics. The yeast strain EC1118 had the most desirable properties, and is considered suitable for kiwifruit fermentation. Valuable attributes of wine fermented by this yeast include overall sensory acceptance, an appropriate level of total phenolics, and good antioxidant activity.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.12-16
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• 1995

Medium components for lactic acid production were optimized with a strain of Lactobacillus sp., isolated by our Lab. Nitrogen source was the key component and manganese ion was also important for lactic acid production in this strain. Optimal concentration of manganese ion was 0.03 g/l as MnSO$_{4}$ 4 - 5 H$_{2}$O base. Other mineral elements, however, had little effect on it. Among the nitrogen sources we examined, yeast extract showed the highest productivity. Yeast extract, the exellent but very expensive medium component, could be partially replaced by soytone until 60% dry base with higher productivity, or by tryptone enforced with vitamines and nucleic acids. In order to replace yeast extract completely, we examined several inexpensive nitrogen sources and their enzymatic hydrolyzates. The hydrolyzate of vital wheat gluten was the best of them.

• Microbiology and Biotechnology Letters
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• v.25 no.5
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• pp.512-519
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• 1997

RNA accumulating strain of Torulopsis versatilis MT-1 was cultured in molasses medium for higher contents of RNA in cell. Yeast cells were harvested at logarithmic phase on synchronous culture. Yield of cells on dry base to input sugar was 59.5%. Crude protein content was 55.1% in cell. RNA content was 13.9%. Some problems found in the process for the preparation of yeast extracts were improved by the addition of culture broth of Streptomyces faecalis MSF which secrete RNase (5' nuclease and 5' adenylic acid deaminase). When the culture broth of S. faecalis MSF was added in autolysis process 46% of RNA in cell was converted to I and G(5' inosinic acid and 5' guanylic acid) in extract. By addition of 3-7% culture broth of S.faecalis MSF in autolysis or enzymolysis process at the start or early stage, RNA in extract was converted easily to I and G and protein in cells was easily extracted and hydrolyzed to amino acid. Taste of those yeast extracts was delicious. The yeasty smell in yeast extracts was removed. And cell debris was easily removed from extract.

• Korean Journal of Microbiology
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• v.16 no.3
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• pp.103-110
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• 1978

Saccharomyces cerevisiae strain M. was cultured in a molasses-containing media with different amounts of phosphorous and nitrogen sources. The effects of constituents of the cell on the functional activity as well as sensitivity of it were investigated, the results obtained being summarised as follows : Both the thermotolerance and dry tolerance of the yeast cell were higher when the more carbohydrate and thehalose were present in the yeast cell. During the drying, the rate of dead cell was noted increasing and the fermentability decreasing, but it was more remarkable at early stage of the decreasing rate of drying, and at the same time increasing rate of dead cell and decrease of fermentability were more remarkable in the yeast cell containing much protein. In this case the speed of drying was slower. The trehalose content in the yeast cell increased during early stage of the drying and this increase was higher when content of trehalose and carbohydrate in the initial yeast cell was relatively high.

• The Korean Journal of Food And Nutrition
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• v.16 no.3
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• pp.203-208
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• 2003

In wine making, to perform yeast culture effectively that is the most important factor, 5 (Montrachet, Pasteur Champagne, Epernay II, prise de Mousse, Lalvin W15) representative active dry yeasts were selected. These are results about physicochemical properties. As a consequence of examining the survival rate in both 17% ethanol solution and 200ppm sulfite solution after 72 hours, Lalvin W15 strain was the highest among the 5 representative active dry yeasts. Moreover, in 1% citric acid solution, the survival rate of Pasteur Champagne after 72 hours was the highest one. As a result of experiment of red wine that is fermented by 5 different active dry yeasts, the highest one of total acidity was must of Lalvin W15. And then, the must of the Epernay II contains the highest ethanol content. Regarding of the content of organic acid, the wine that is fermented by Prise de mousse was the highest one and the order could be explained by Tartaric > Malic > Citric.

• Journal of Life Science
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• v.18 no.4
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• pp.447-453
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• 2008

Zinc is an essential trace element in Human Being. Highly zinc containing yeast strain isolated from the tropical fruit, rambutan and the zinc concentration in this yeast strain was 306 ppm (30.6 mg%)per dry matter basis. This strain was found to be a rounded type, normal size, and multi-polar budding. Phylogenetic analysis using the ITS1-5.85 rDNA sequences from isolated strain is most similar to yeast Saccharomyces cerevisiae at the level of nucleotide sequence identity at 99%. This strain was produced alcohol by about 12% using fully colonized koji-rice with Aspergillus oryzae. In conclusion, the isolated strain was found to be closely related to the S. cerevisiae based on its morphological and physiological properties, and alcohol fermentation. The phylogenetic analysis of strain FF-10 using ITS 5.8S rDNA sequence data also supported the closely related to the S. cerevisiae. Accordingly, the isolated yeast was named as S. cerevisiae FF-10. Further studies on the best culture conditions for zinc production from zinc-enriched S. cerevisiae FF-10 are under investigation.

• Korean Journal of Microbiology
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• v.19 no.4
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• pp.163-173
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• 1981

The distribution of methanol-assimilating yeasts on three different sources (elm bark, soil and fresh-water mud) and the growth conditions of a new strain of Candidaboidinii (SIO) wereexamines. From 150 samples, 91 methanol yeasts were isolated through enrichment culture ; they were identified as 77 strains of Candida boidinii including four new strains, 5 isolates of Torulopsis pinus, 3 strains of Hansenula polymorpha and one sstrain of Pichia pastoris respectively. The comparison of these yeasts with three sources indicated that decaying bark of elm tree other two, and that Gandida boidinii was most frequently distributed in all three sources. Four new strains of Candida boidinii were freshly isolated and their taxonomical properties were discussed. Of them, SIO strain was selected and characterized for its growth on methanol. This yeast could grow well on less than 1%(v/v) methanol. However, its growth was inhibited at 10% methanol. The cell yield was 3.1g (dry weight) per 1000ml of mineral mediurr, containing 1%(v/v) methanol as well as 01.% yeast extract as additive. The concentration of 0.1% yeast extract appears to be effective for the biomass production. Optimum conditions for growth on methanol was found to be : $28^{\circ}C,\;NH_4^+$ as nitrogen sources, thiamine as vitamin, and pH 4.5 to 6.0. The cell composition was as follows : crude protein and nucleic acids were 54% and 7% respectively. The amino acids were also described.