• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.737-748
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• 2010

Glutaminase production in Zygosaccharomyces rouxii by solid-state fermentation (SSF) is detailed. Substrates screening showed best results with oatmeal (OM) and wheatbran (WB). Furthermore, a 1:1 combination of OM:WB gave 0.614 units/gds with artificial sea water as a moistening agent. Evaluation of additional carbon, nitrogen, amino acids, and minerals supplementation was done. A central composite design was employed to investigate the effects of four variables (viz., moisture content, glucose, corn steep liquor, and glutamine) on production. A 4-fold increase in enzyme production was obtained. Studies were undertaken to analyze the time-course model, the microbial growth, and nutrient utilization during SSF. A logistic equation ($R^2$=0.8973), describing the growth model of Z. rouxii, was obtained with maximum values of ${\mu}_m$ and $X_m$ at $0.326h^{-1}$ and 7.35% of dry matter weight loss, respectively. A goodfit model to describe utilization of total carbohydrate ($R^2$=0.9906) and nitrogen concentration ($R^2$=0.9869) with time was obtained. The model was used successfully to predict enzyme production ($R^2$=0.7950).

• Microbiology and Biotechnology Letters
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• v.16 no.2
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• pp.142-149
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• 1988

This experiment was carried out to obtain a hybrid with potent ethanol fermenting ability, by means of protoplast fusion between a thermophilic strain (D-71) of Saccharomyces cerevisiae and an osmotolerant strain (SR-S) of Zygosaccharomyces rouxii. The conditions for formation of protoplasts from both strains and for their fusion and regeneration were studied. Favorable conditions for formation of protoplasts from Saccharomyces cerevisiae D-71 were : treatment of the cells at late-exponential phase with 2-mercaptoethanol (l% v/v) for 10 minutes in the presence of 0.5M sorbitol, then incubation for 60 minutes in the set medium containing Zymolyase-20T (4mg/$m\ell$) ; and from Zygosaccharomyces rouxii SR-S were : treatment of the cells at mid-exponential phase with 2-mercaptoethanol (1% v/v) for 10 minutes in the presence of 0.5M or 1M mannitol, then incubation for 120 minutes in the set medium containing Zymolyase-20T(4mg/$m\ell$). The protoplasts of parental cells were fused in the presence of 20mM CaCl$_2$, 0.5M sorbitol and 40% of polyethyleneglycol (M.W 4000), then fusants obtained were selected as regenerated colonies which embedded and grown in the minimal medium containing 3% of agar. The frequencies of fusant formation were 1.2$\times$10$^{-6}$ to 9.1$\times$10$^{-6}$ for the regenerated protoplast.

• Journal of Microbiology and Biotechnology
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• v.3 no.1
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• pp.24-30
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• 1993

In order to develop a novel yeast which produces the charateristic aroma of soy sauce, a protoplast fusion between Zygosaccharomyces rouxii WFS4 and Torulopsis versatilis IAM 4993 was carried out. Auxotrophic mutants as selective markers were obtained from Zygosaccharomyces rouxii and Torulopsis versatilis by treatment of N-methyl-N -nitro-N-nitrosoguanidine. The conditions of the protoplast formation and the regeneration for fusion were examined. The protoplast fusion using polyethylene glycol 4000 led to the fusion frequency of $4~5{\times}10^{-7}\;cells/ml$. Among fusants, a fusant ST723-F31 presented the best results in terms of the aromaticity of fragrance, the growth pattern, the resistance against salt and the degree of growth according to pH. It makes easy to control the production and the balance of aroma components so that it gives a good flavor, shortens the fermentation period and, simplifies the preparation process when using a bioreactor into which fusant is immobilized.

• The Korean Journal of Food And Nutrition
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• v.10 no.1
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• pp.97-101
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• 1997

Gas formation, and container swelling and explosion during the distribution of commercial soy sauce is an important problem to be solved. Six yeasts were isolated from soy sauce returned because of container swelling. Three isolates (SS-1, SS-2, SP-1) formed film on soy sauce while others did not. Five isolates(SS-1, SS-2, SS-4, SP-1, SP-2) actively fermented soy sauce to produce gas and all were identified as Zygosaccharomyces rouxii, and one other isolate (SS-3) fermented soy sauce very weakly and was identified as Candida globosa.

• The Korean Journal of Mycology
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• v.39 no.3
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• pp.229-230
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• 2011

Growth profiles of Candida krusei KCTC 7213, Torulopsis sphaerica KCTC 7138 and Zygosaccharomyces rouxii KCCM 12066 in pear marc extract were determined. Candida krusei KCTC 7213 showed the highest growth in 20 hr cultivation at $30^{\circ}C$, whereas both of Torulopsis sphaerica KCTC 7138 and Zygosaccharomyces rouxii KCCM 12066 established maximal growth by 25 hr of cultivation at $30^{\circ}C$ in pear marc extract. However, all of yeasts showed lower growth in pear marc extracts rather than those of YEPD medium.

• Journal of Microbiology and Biotechnology
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• v.30 no.1
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• pp.62-70
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• 2020

Zygosaccharomyces rouxii is an important yeast that is required in the food fermentation process due to its high salt tolerance. In this study, the responses and resistance strategies of Z. rouxii against salt stress were investigated by performing physiological analysis at membrane level. The results showed that under salt stress, cell integrity was destroyed, and the cell wall was ruptured, which was accompanied by intracellular substance spillover. With an increase of salt concentrations, intracellular Na⁺ content increased slightly, whereas intracellular K⁺ content decreased significantly, which caused the increase of the intracellular Na⁺/K⁺ ratio. In addition, in response to salt stress, the activity of Na⁺/K⁺-ATPase increased from 0.54 to 2.14 μmol/mg protein, and the ergosterol content increased to 2.42-fold to maintain membrane stability. Analysis of cell membrane fluidity and fatty acid composition showed that cell membrane fluidity decreased and unsaturated fatty acid proportions increased, leading to a 101.21% rise in the unsaturated/saturated fatty acid ratio. The results presented in this study offer guidance in understanding the salt tolerance mechanism of Z. rouxii, and in developing new strategies to increase the industrial utilization of this species under salt stress.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.2
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• pp.268-274
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• 1998

The traditional kanjang has been prepared by mixing meju and 18% saline solution, and fermenting for 60 days. The traditional kanjang is very salty and inferior in flavor and taste comparing with commercial fermented soy sauce. To improve the quality of traditional kanjang, Zygosaccharomyces rouxii H-62, a flavor-related mutant, was inoculated during fermentation. It was found that the addition of Z rouxii helped to improve the organoleptic quaity of traditional kanjang. The optimal condition for preparing traditional kanjang was to use 5L of 15.5% saline solution per meju. Meju must be cut into 12 pieces to get a proper total nitrogen and pure extract content. The optimal fermentatin temperature was 3$0^{\circ}C$. The prepared kanjang contained over 0.8% total nitrogen and 6.0% pure extract after 60 days of fermentation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.11
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• pp.1486-1490
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• 2007

This study was performed to evaluate the effect of the fermented beef rib sauce (FBS) on the change of quality characteristics and sensory properties of aged and seasoned beef rib with FBS. The FBS was manufactured by fermentation with Zygosaccharomyces rouxii Y-80 yeast in raw sauce ingredients. The decreasing changes of pH of seasoned beef rib with FBS showed a similar pattern as compared with seasoned beef rib by non-fermented beef rib sauce (NFBS) during aging periods. The cooking loss of the seasoned beef rib with FBS and NFBS exhibited minor changes, respectively. Water holding capacity of the seasoned beef rib with FBS was nearly unchanged, but that of the seasoned beef rib with NFBS increased from 83% to 91% after 5 day aging. Shear forces of the seasoned beef rib with FBS were lower than those of the seasoned beef rib with NFBS. The yellowness and lightness of the seasoned beef rib with FBS decreased as compared with the seasoned beef rib with NFBS, but redness of the seasoned beef rib with FBS was more stable than that of the seasoned beef rib with NFBS. The sensory evaluation indicated that color, aroma and overall acceptability of the seasoned beef rib with FBS were scored relatively higher than those of the seasoned beef rib with NFBS.

• Korean Journal of Food Science and Technology
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• v.38 no.5
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• pp.712-716
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• 2006

Saccharomyces cerevisiae and Zygosaccharomyces rouxii were electrofused and fermented in germaniumfortified nutrients to produce high-yield, organic germanium. The conditions for the preparation of protoplasts from both strains and for electrofusion were studied. The protoplasts of both cells formed long pearl chains and the cell membranes were lysed and fused through cellulase and high frequency voltage $(450{\sim}750V/128{\sim}512\;{\mu}sec)$. The fusants with the fastest growth were selected, and then characterized for their carbohydrate usage and tolerance to glucose and salts. The glucose tolerance of the fusants was better than that of S. cerevisiae and similar to that of Z. rouxii. The fusants appeared to have resistance to 12% NaCl. The cell size of the fusants was greater than that of the parental strains. The fusant cells contained more gemlanium than the parental cells did. The electrofusion of S. cerevisiae and Z. rouxii increased the cell capacity and accumulation of germanium in the yeasts. This method was proved to be effective to produce a high quantity of organic germanium.

• Applied Biological Chemistry
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• v.39 no.4
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• pp.255-259
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• 1996

In order to improve the quality of commercially manufactured Doenjang, yeast florae, gas and alcohol formation during fermentation of Doenjang were periodically examined. Candida rugosa, Candida zeylanoides, Pichia farinosa Saccharomyces cerevisiae and Zygosaccharomyces rouxii were isolated and identified from Doenjang at various fermentation stage. S. cerevisiae and Z. rouxii showed distintive gas and alcohol formation activities and the distribution ratio of Z. rouxii was 26% at 14 days and 76% as prevailed yeast strain after 30 days fermentation, respectively. Ethanol content of Doenjang was gradually increased into 2.19% at final stage of fermentation. The amount of gas generated during fermentation was 9.75 ml/g after 14 days, 4.5 ml/g after 30 days and decreased into negligible amount after 45 days fermentation. These inhibitory effects on gas generation by fermentation period would be ascribed to the ethanol Produced for fermentation. This results suggest that gas generation in commercially manufactured Doenjang could be eliminated through the effective control of fermentation by yeast without application of any preservatives.