• KSBB Journal
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• v.8 no.5
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• pp.495-503
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• 1993

To investigate the characteristics of growth and oil production of peppermint cells during a batch culture, cells derived from peppermint callus was cultivated in an air bubble reactor. During the batch culture, effects of inoculum size, abiotic stress, yeast elicitor, and two stage culture on the cell growth, the productivity of oleolesin, and the formation of flavor components were determined and also the sugar concentrations and kinetics of cell growth were analyzed. Among the various sizes of inoculum, the culture with 2.0% packed cell volume inoculum showed the optimum condition for cell growth in the proposed bioreactor, and the cell yield and essential oil production reached to 5.7g/1 and 0.109g/1, respectively. When the abiotic stress of daily 8hr dark and $10^{\circ}C$ cold treatments were given to the culture cell growth decreased but essential oil production increased to 0.546g/l. In a modified Lin-Staba medium in which 100mg/l yeast extract as an elicitor was added to the culture, the cell growth and oil production increased, and menthol content was 22.5% of oil. In the two stage culture, in which the basic culture conditions of 27$^{\circ}C$, light, and without elicitor were employed during the first six days followed by the second stage with daily 8hr treatment of cold and dark condition, and also with yeast extract as an elicitor, cell growth decreased after eight days, essential oil production was not increased, and menthol was not detected. Dry cell yield was 0.38g dry cell/g sugar and specific growth rate was 0.25 day-1. The major terpenoid in the oil was not the menthol but pulegone and piperitone, precursors of menthol were accumulated. However, when yeast elicitor was added, menthol was produced to the level of 22.5% which was the highest value in the peppermint cell culture reported so far.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.3
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• pp.352-356
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• 2002

One hundred-fifty lactating, multiparous cow at post-peak of lactation were used to examine the effect of dietary yeast supplementation on milk production, milk composition and ruminal fermentation. The cows were randomly allocated to three groups of fifty cows each: a control group fed on a basal diet without yeast supplementation and two groups fed on basal diets supplemented with one of two commercial sources of yeast cultures, given at the rates of 15 g/head/d ($YC_1$) and 50 g/head/d ($YC_2$), respectively, as per manufacturers' recommendation. Daily milk production was recorded for all cows, while milk samples were taken randomly from ten cows per group for two consecutive days at two-week intervals for chemical analysis of the milk. Rumen fluids were also analyzed for ammonia nitrogen and volatile fatty acids. The results indicated that cows consuming diets supplemented with yeast culture tended to decrease their dry matter intake and to increase their milk yield. Cows fed $YC_2$ supplemented diet produced more milk and 4% fat corrected milk than those fed either $YC_1$-supplemented diet or the control. The highest milk fat percentage was obtained in cows fed $YC_2$ supplemented diet while the highest percentages of protein, lactose, total solids and solids not fat were recorded in cows fed $YC_1$. Rumen ammonia nitrogen concentration decreased significantly after yeast culture supplementation. Molar proportion of volatile fatty acids did not change significantly with yeast supplementation.

• 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.29 no.4
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• pp.234-239
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• 2001

In order to maximize the RNA accumulation and biomass production is Saccharomyces cerevisiae MTY62, a high-content RNA yeast strain, batch and fed-batch cultures were performed. Among the feeding modes of fed-batch cultures examined, the intermittent feeding mode R\`(IFB-lV), in which 50 ml of 40% molasses and 20% com steep liquor (CSL) solution was intermittently fed for 5 times, resulted in the cell concentration of 33.8 g- dry cell weight/1 and the RNA concentration of 5221 mg-/l, and RNA content of 153 mg-RNA/g-dry cell weight. The constant fed-batch with feeding mode III (CFB-III), in which the feeding rate of 40% molasses and 20% CSL solution was stepwisely decreased from 48 mph (9-13 h), to 24 mph (13-21 h), and to 18 ml/h (21∼ 48 h), gave the highest cell concentration of 42.7 g-dry ceil weigh71 and R7IA concentration of 5536 mg-RNA/1, which were about 2.4-fold and 1.9-fold increased levels, respectively, compared to the results of batch culture. However, the RNA con- tent of 130 mg-RNA/g-dry cell weight of the fed-batch was lower than that of the batch culture (171 mg-RNA/g-dry cell weight) and other fed-batch cultures. When the specific growth rates in the fed-batch cultures were increased, the RNA contents increased. This result indicates that the RNA content is adversely proportional to the cell concen- tration. However, at the same specific growth rate, the RNA content was maintained at higher level in the intermit- tent fed-batch than in the constant fed-batch culture.

• The Korean Journal of Mycology
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• v.40 no.4
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• pp.204-209
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• 2012

In this study, a novel yeast, Y111-5 for Makgeolli manufacture was selected from Nuruk yeasts, and its optimal culture condition were investigated. The Y111-5 strain was identified as Saccharomyces cerevisiae by phylogenetic analysis of 18S RNA sequence. The maximal growth was obtained when the yeast was cultivated at $30^{\circ}C$ for 15 h in the medium containing sucrose 9% and yeast extract 5%.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.5
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• pp.639-646
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• 2015

The effects of Saccharomyces cerevisiae supplementation ($6.6{\times}10^8cfu$) and anhydrous ammonia treatment (3%) of wheat straw (WS) were investigated on in-situ dry matter (DM) degradability, and on rumen fermentation and growth performance of lambs. Rumen-fistulated Menemen sheep fed a diet with and without live yeast were used to assess the DM degradability characteristics of WS and ammonia-treated wheat straw ($WS_{NH3}$). Twenty-six yearling Menemen male lambs were fed in four groups. Lambs of control group (WS) received untreated WS without supplemental yeast, whereas other three groups were fed WS treated with anhydrous ammonia ($WS_{NH3}$ group), untreated WS and yeast (WS+YEAST group) or WS treated with anhydrous ammonia and yeast ($WS_{NH3}$+YEAST group). Supplemented live yeast (4 g/d) was added in the diet. Lambs were offered untreated or ammonia treated WS ad-libitum and concentrate was fed at 1% of live body weight. The degradability of the water-insoluble (fraction B) was significantly increased by all of the treatment groups. Potential degradability (A+B), effective DM degradability's (pe2, pe5, and pe8) and average daily weight gain increased only in $WS_{NH3}$+YEAST group (p<0.05). Voluntary DM intake was not increased by the treatments (p>0.05), but voluntary metabolizable energy and crude protein intake were increased by $WS_{NH3}$ and by $WS_{NH3}$+YEAST (p<0.05). Average daily rumen pH was not affected by any of the treatments, but average daily $NH_3$-N was significantly higher in the $WS_{NH3}$ and $WS_{NH3}$+YEAST groups, and total volatile fatty acids were significantly higher in the WS+YEAST and $WS_{NH3}$+YEAST groups. In conclusion, the improvement of feed value of WS was better by the combination of ammonia-treatment and yeast supplementation compared to either treatment alone.

• Food Science of Animal Resources
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• v.43 no.3
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• pp.454-470
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• 2023

This study analyzed the microbiological (Lactobacillus spp., Staphylococcus spp., mold, yeast, aerobic bacteria) and physicochemical properties [pH, salinity, water activity, volatile basic nitrogen (VBN), and thiobarbituric acid reactive substances]. The starters were used by mixing Debaryomyces hansenii separated from Korean Doenjang (D) and fermented sausage (S). The starter was inoculated with dry-cured ham and aged for 6 weeks at 20℃ and 25℃, respectively. The aerobic bacteria, Lactobacillus spp., and Staphylococcus spp. of D, S, and DS treatment showed significantly higher values at 25℃ than at 20℃. Among them, S25 treatment showed a high tendency. At week 6, the mold of the S25 treatment was significantly higher than the S20 treatment, and the yeast was higher in 25℃ than 20℃ (p<0.05). The pH of all treatment groups increased with the aging period. Compared with that at 25℃, the pH was significantly higher at 20℃ (p<0.05). The water activity showed a significant decrease as the aging period increased, and the treatment of D25, S20, and DS20 showed a significantly higher value at week 6 (p<0.05). Compared with that at 20℃, the VBN content was higher at 25℃. At week 6, the VBN contents of the C20, S25, and DS25 groups were higher than those of the other treatment groups. Therefore, inoculation of D. hansenii separated from fermented sausage produced in Korean starter at 25℃ is expected to improve the safety of harmful microorganisms and physiochemical properties in dry-cured ham.

• Journal of Aquaculture
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• v.9 no.4
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• pp.345-351
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• 1996

Mass production of resting egg of the rotifer, Brachionus plicatilis was carried out in 1 $m^3$ tank for L-type rotifer and in 1 $m^3$ and 4 $m^3$ tank for S-type rotifer. L-type rotifer was fed on concentrated Chlorella + baker's yeast and only baker's yeast for 15 days. S-type rotifer was fed on concentrated Chlorella in 1 $m^3$ tank for 7 days and frozen Chlorella + baker's yeast in 4 $m^3$ for $6\~8$ days. Total number of resting egg and number of resting egg from $10^8$ rotifers and 1 g dry weight diet for L-type rotifer fed on Chlorella + baker's yeast were $54.5{\times}10^6$ eggs, $30.5{\times}10^6$ eggs and $100{\times}10^3$ eggs, respectively. These were higher than those of rotifer fed on baker's yeast only. Total number of resting egg and number of resting egg from $10^8$ rotifers and 1 g dry weight diet for S-type rotifer fed on concentrated Chlorella in 1 $m^3$ tank were $50\~104{\times}10^6$ eggs, $47\~82{\times}10^6$ eggs and $136\~260{\times}10^3$ eggs, respectively. In 4 $m^3$ tank with frozen Chlorella + baker's yeast, these were $149\~567{\times}10^6$ eggs, $36\~123{\times}10^6$ eggs and $131\~338{\times}10^3$ eggs, respectively. This result suggests that S-type rotifer are better than L-type rotifer for the mass production of resting egg of the Korean rotifer.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.6
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• pp.856-863
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• 2013

An in vitro gas production technique was used in this study to elucidate the effect of two strains of active live yeast on methane ($CH_4$) production in the large intestinal content of pigs to provide an insight to whether active live yeast could suppress $CH_4$ production in the hindgut of pigs. Treatments used in this study include blank (no substrate and no live yeast cells), control (no live yeast cells) and yeast (YST) supplementation groups (supplemented with live yeast cells, YST1 or YST2). The yeast cultures contained $1.8{\times}10^{10}$ cells per g, which were added at the rates of 0.2 mg and 0.4 mg per ml of the fermented inoculum. Large intestinal contents were collected from 2 Duroc${\times}$Landrace${\times}$Yorkshire pigs, mixed with a phosphate buffer (1:2), and incubated anaerobically at $39^{\circ}C$ for 24 h using 500 mg substrate (dry matter (DM) basis). Total gas and $CH_4$ production decreased (p<0.05) with supplementation of yeast. The methane production reduction potential (MRP) was calculated by assuming net methane concentration for the control as 100%. The MRP of yeast 2 was more than 25%. Compared with the control group, in vitro DM digestibility (IVDMD) and total volatile fatty acids (VFA) concentration increased (p<0.05) in 0.4 mg/ml YST1 and 0.2 mg/ml YST2 supplementation groups. Proportion of propionate, butyrate and valerate increased (p<0.05), but that of acetate decreased (p<0.05), which led to a decreased (p<0.05) acetate: propionate (A: P) ratio in the both YST2 treatments and the 0.4 mg/ml YST 1 supplementation groups. Hydrogen recovery decreased (p<0.05) with yeast supplementation. Quantity of methanogenic archaea per milliliter of inoculum decreased (p<0.05) with yeast supplementation after 24 h of incubation. Our results suggest that live yeast cells suppressed in vitro $CH_4$ production when inoculated into the large intestinal contents of pigs and shifted the fermentation pattern to favor propionate production together with an increased population of acetogenic bacteria, both of which serve as a competitive pathway for the available H2 resulting in the reduction of methanogenic archaea.

• Animal Bioscience
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• v.37 no.7
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• pp.1185-1195
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• 2024

Objective: This meta-analysis aimed to evaluate the impact of wilted and unwilted silage on various parameters, such as nutrient content, fermentation quality, bacterial populations, and digestibility. Methods: Thirty-six studies from Scopus were included in the database and analyzed using a random effects model in OpenMEE software. The studies were grouped into two categories: wilting silage (experiment group) and non-wilting silage (control group). Publication bias was assessed using a fail-safe number. Results: The results showed that wilting before ensiling significantly increased the levels of dry matter, water-soluble carbohydrates, neutral detergent fiber, and acid detergent fiber, compared to non-wilting silage (p<0.05). However, wilting significantly decreased dry matter losses, lactic acid, acetic acid, butyric acid, and ammonia levels (p<0.05). The pH, crude protein, and ash contents remained unaffected by the wilting process. Additionally, the meta-analysis revealed no significant differences in bacterial populations, including lactic acid bacteria, yeast, and aerobic bacteria, or in vitro dry matter digestibility between the two groups (p>0.05). Conclusion: Wilting before ensiling significantly improved silage quality by increasing dry matter and water-soluble carbohydrates, as well as reducing dry matter losses, butyric acid, and ammonia. Importantly, wilting did not have a significant impact on pH, crude protein, or in vitro dry matter digestibility.