• Korean Journal of Environmental Biology
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• v.28 no.2
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• pp.101-107
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• 2010

Metal ions are essential to life. However, some metals such as mercury are harmful, even when present at trace amounts. Toxicity of mercury arises mainly from its oxidizing properties. Ionizing radiation (IR) is an active tool for destruction of cancer cells and diagnosis of diseases, etc. IR induces DNA double strand breaks in the nucleus, In addition, it causes lipid peroxidation, ceramide generation, and protein oxidation in the membrane, cytoplasm and nucleus. Yeasts have been a commonly used material in biological research. In yeasts, the physiological response to changing environmental conditions is controlled by the cell types. Growth rate, mutation and environmental conditions affect cell size and shape distributions. In this work, the effect of IR and mercury chloride (II) on the morphology of yeast cells were investigated. Saccharomyces cerevisiae cells were treated with IR, mercury chloride (II) and IR combined with mercury chloride (II). Non-treated cells were used as a control group. Morphological changes were observed by a scanning electron microscope (SEM). The half-lethal condition from the previous experimental results was used to the IR combined with mercury. Yeast cells were exposed to 400 and 800 Gy at dose rates of 400Gy $hr^{-1}$ or 800 Gy $hr^{-1}$, respectively. Yeast cells were treated with 0.05 to 0.15 mM mercury chloride (II). Oxidative stress can damage cellular membranes through a lipidic peroxidation. This effect was detected in this work, after treatment of IR and mercury chloride (II). The cell morphology was modified more at high doses of IR and high concentrations of mercury chloride(II). IR and mercury chloride (II) were of the oxidative stress. Cell morphology was modified differently according to the way of oxidative stress treatment. Moreover, morphological changes in the cell membrane were more observable in the frequently stress treated cells than the temporarily stress treated cells.

• BMB Reports
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• v.38 no.6
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• pp.661-667
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• 2005

Since conflicting results have been reported on non-specific immune response in type 1 diabetes, this study evaluates polymorphonuclear neutrophil (PMN) functions in the infection free Long Evan diabetic rats (type 1) by using tests that include: polarization assay, phagocytosis of baker's yeasts (Saccharomyces cerevisiae) and nitroblue tetrazolium (NBT) dye reduction. Polarization assay showed that neutrophils from diabetic rats were significantly activated at the basal level compared to those from the controls (p < 0.001). After PMN activation with N-formyl-methionyl-leucyl-phenylalanine (FMLP), control neutrophils were found to be more polarized than those of the diabetic neutrophils and the highest proportions of polarization were found to be 67% and 57% at $10^{-7}\;M$ FMLP, respectively. In the resting state, neutrophils from the diabetic rats reduced significantly more NBT dye than that of the controls (p < 0.001). The percentages of phagocytosis of opsonized yeast cells by the neutrophils from control and diabetic rats were 87% and 61%, respectively and the difference was statistically significant (p < 0.001). Evaluation of the phagocytic efficiency of PMNs revealed that control neutrophils could phagocytose $381{\pm}17$ whereas those from the diabetic rats phagocytosed $282{\pm}16$ yeast cells, and the efficiency of phagocytosis varied significantly (p < 0.001). Further, both the percentages of phagocytosis and the efficiency of phagocytosis by the diabetic neutrophils were inversely related with the levels of their corresponding plasma glucose (p = 0.02; r = -0.498 and p < 0.05; r = -0.43, respectively), which indicated that increased plasma glucose reduced the phagocytic ability of neutrophils. Such relationship was not observed with the control neutrophils. These data clearly indicate that PMN functions are altered in the streptozotocin (STZ) - induced diabetic rats, and hyperglycemia may be the cause for the impairment of their functions leading to many infectious episodes.

• Journal of Microbiology and Biotechnology
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• v.22 no.8
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• pp.1101-1106
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• 2012

Market fresh makgeolli was stored at different temperatures of $4^{\circ}C$ and $25^{\circ}C$ to assess the change of the microbial diversity according to the storage temperature and period. Yeast counts increased until day 3 of storage and decreased thereafter. General and lactic acid bacterial counts continuously increased during storage. The data indicated that the control of growth of microorganisms, particularly general bacteria and lactic acid bacteria (LAB), is essential. Total acid levels started to decrease in the makgeolli stored at $4^{\circ}C$, and increased from day 6 of storage in the makgeolli stored at $25^{\circ}C$. The increase of total acid in the non-refrigerated condition greatly affected the quality of makgeolli. In both the fresh makgeolli samples stored at $4^{\circ}C$ and $25^{\circ}C$, yeast (Saccharomyces cerevisiae) and molds (Aspergillus tubingensis, Candida glaebosa, and Aspergillus niger) were noted. Denaturing gradient gel electrophoresis (DGGE) band patterns were almost constant regardless of the storage period. As for bacteria, Lactobacillus crustorum, L. brevis, and Microlaena stipoides were found in the makgeolli stored at $4^{\circ}C$, and L. crustorum, Lactobacillus sp., L. plantarum, L. brevis, L. rhamnosus, and L. similis were found in the makgeolli stored at $25^{\circ}C$. In particular, in the makgeolli stored at $25^{\circ}C$, L. crustorum and L. plantarum presented dark bands and were identified as the primary microorganisms that affected spoilage of fresh makgeolli.

• Microbiology and Biotechnology Letters
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• v.44 no.4
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• pp.529-534
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• 2016

Bioethanol was produced using the separate hydrolysis and fermentation (SHF) method with macroalgal polysaccharides from the seaweed, Undaria pinnatifida as biomass. This study focused on the pretreatment, enzymatic saccharification, and fermentation of yeasts in co-culture. Ethanol fermentation with 14.5% (w/v) seaweed hydrolysate was performed using the yeasts, Saccharomyces cerevisiae KCTC 1126 alone, Pichia angophorae KCTC 17574 alone, and their co-cultures with the yeasts either adapted to mannitol or not. Among the combinations, the co-culture of non-adapted S. cerevisiae and P. angophorae adapted to mannitol showed high bioethanol production of 12.2 g/l and an ethanol yield ($Y_{EtOH}$) of 0.41. Co-culture in the SSF process was employed in this study, to increase the ethanol yields of 35.2% and reduction of 33.3% in fermentation time. These results provide suitable information on ethanol fermentation with marine seaweeds for bioenergy production.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.11
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• pp.1592-1598
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• 2015

This study was conducted to determine the effects of feeding a trace minerals-fortified microbial culture (TMC) on the performance and carcass characteristics of late-fattening Hanwoo steers. A mixture of microbes (0.6% [v/w] of Enterobacter sp., Bacillus sp., Lactobacillus sp., and Saccharomyces sp.) was cultured with 99% feedstuff for ensiling and 0.4% trace minerals (zinc, selenium, copper, and cobalt). Sixteen late-fattening steers (mean age, 21.8 months) were allocated to two diets: a control diet (concentrate mix and rice straw) and a treated diet (control diet+3.3% TMC). At a mean age of 31.1 months, all the steers were slaughtered. The addition of TMC to the diet did not affect the average daily weight gain of the late fattening steers, compared with that of control steers. Moreover, consuming the TMC-supplemented diet did not affect cold carcass weight, yield traits such as back fat thickness, longissimus muscle area, yield index or yield grade, or quality traits such as meat color, fat color, texture, maturity, marbling score, or quality grade. However, consumption of a TMC-supplemented diet increased the concentrations of zinc, selenium, and sulfur (p<0.05) in the longissimus muscle. With respect to amino acids, animals consuming TMC showed increased (p<0.05) concentrations of lysine, leucine, and valine among essential amino acids and a decreased (p<0.05) concentration of proline among non-essential amino acids. In conclusion, the consumption of a TMC-supplemented diet during the late-fattening period elevated the concentrations of certain trace minerals and essential amino acids in the longissimus muscle, without any deleterious effects on performance and other carcass characteristics of Hanwoo steers.

• Journal of Microbiology and Biotechnology
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• v.21 no.5
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• pp.519-524
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• 2011

The correlation between alcoholic fermentation rate, measured as carbon dioxide ($CO_2$) evolution, and the rate of hydrogen sulfide ($H_2S$) formation during wine production was investigated. Both rates and the resulting concentration peaks in fermentor headspace $H_2S$ were directly impacted by yeast assimilable nitrogenous compounds in the grape juice. A series of model fermentations was conducted in temperature-controlled and stirred fermentors using a complex model juice with defined concentrations of ammonium ions and/or amino acids. The fermentation rate was measured indirectly by noting the weight loss of the fermentor; $H_2S$ was quantitatively trapped in realtime using a pre-calibrated $H_2S$ detection tube which was inserted into a fermentor gas relief port. Evolution rates for $CO_2$ and $H_2S$ as well as the relative ratios between them were calculated. These fermentations confirmed that total sulfide formation was strongly yeast strain-dependent, and high concentrations of yeast assimilable nitrogen did not necessarily protect against elevated $H_2S$ formation. High initial concentrations of ammonium ions via addition of diammonium phosphate (DAP) caused a higher evolution of $H_2S$ when compared with a non-supplemented but nondeficient juice. It was observed that the excess availability of a certain yeast assimilable amino acid, arginine, could result in a more sustained $CO_2$ production rate throughout the wine fermentation. The contribution of yeast assimilable amino acids from conventional commercial yeast foods to lowering of the $H_2S$ formation was marginal.

• ALGAE
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• v.26 no.4
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• pp.343-350
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• 2011

Fermentation and enzyme-assisted extraction (EAE) improve nutritional and functional properties of foods by increasing the extraction of active compounds, ingestion rates, and body absorption. In this study, we investigated whether applying the EAE process improves the extraction and isolation efficiency of a polysaccharide from fermented Ecklonia cava (FE), which inhibited NO production in lipopolysaccharide (LPS)-activated RAW 264.7 cells. The results showed that the FE using the fungi Candida utilis and two different bacteria, namely Lactobacillus brevis and Saccharomyces cerevisiae increased protein and carbohydrate contents in comparison with those in non-fermented E. cava (NE). Aqueous extracts of fermented E. cava increased extraction yields and carbohydrate content, compared with the aqueous extract of NE. In addition, treating LPS-stimulated RAW 264.7 cells with aqueous extracts resulted in reduced NO production compared to that in LPS-treated cells. Ten EAEs of L. brevis-fermented E. cava (LFE) improved NO inhibitory effects in LPS-activated RAW 264.7 cells and the Viscozyme extract (VLFE) from the resulting extracts showed the highest NO inhibitory effect. We found that the >30 kDa fraction of VLFE led to markedly high inhibition of LPS-induced NO production as compared to that in the <30 kDa fraction. The crude polysaccharide isolated from >30 kDa fraction (VLFEP) consisted of fucose and markedly decreased NO production induced by LPS stimulation. VLFEP could be useful as an anti-inflammatory agent to suppress macrophage activation.

• The Korean Journal of Mycology
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• v.22 no.4
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• pp.332-337
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• 1994

Under standard condition (Han, et al., 1990: glucose 1%-nitrate 0.1% minimal medium, 30 ml in 9 cm plate, $10^6$ cells of inoculum per plate), wild type of Aspergillus nidulans developed both sexual and asexual organs in ballance, while velA1 mutant developed asexual ones preferentially. Increase of glucose concentration did not significantly affect the asexual sporulation. However, development of sexual organs were largely affected. It was greatly enhanced when favorable nitrogen source, for example, casein hydrolysate was added, which is contrary to the case of Neurospora or Saccharomyces where limitation of N source induces sexual development. On most of moderate C sources asexual development in $velA^+$ strain was largely inhibited except acetate on which only asexual spores were produced, while that in velA1 mutant strain was not affected. Lactose promoted the sexual development even in velA1 mutant indicating that lactose itself or its metabolic intermediate may induce sexual development independent of allelic state of velA gene. On other moderate favorable C sources, glycerol, galactose and ethanol, asexual development was largely inhibited in $velA^+$ strain but not in velA1 mutant strain. Sexual organs were, however, never produced on acetate. These results suggested that asexual development of wild type is largely dependent on C sources and the velA gene is involved in the repression of asexual development in not-enough-grown (non-competent) thalli resulting in preferential progression of sexual development.

• Korean Journal of Environmental Agriculture
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• v.36 no.2
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• pp.129-134
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• 2017

BACKGROUND: Yeasts are used in a variety of industries. However, most industries are biased toward Saccharomyces cerevisiae ; so we sought to explore non-conventional yeasts (NCY). This study aimed to isolate yeasts from seawater collected from the East Sea of Korea and to analyze the NCY. METHODS AND RESULTS: We first collected seawater and performed pure isolation using four kinds of medium (GPY, DOB + CSM, DG18, and SCG). In total, 314 strains and 17 genera were isolated by ITS sequencing, including Aureobasidum pullulans (236 strains), Cryptococcus (19 strains), Cystobasidium (18 strains), and Rhodotorula (9 strains). Upon in-depth analysis, A. pullulans, the most dominant genus (236 strains), was divided into Group II (147 strains), Unknown I (8 strains), and Unknown II (49 strains). CONCLUSION: In this study, a total of 314 strains were isolated from seawater; many of these yeasts have been found and reported in seawater previously. In-depth analysis of A. pullulans, showed the dominance of Group I (21 strains) and Group II (147 strains) We also discovered Unknown I (8 strains) and Unknown II (49 strains), which have not been reported previously.

• 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.