• Mycobiology
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• v.51 no.6
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• pp.379-387
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• 2023

In this study, twenty-five yeast strains were isolated from soil samples collected in the gold mining ore in Gia Lai, Vietnam. Among them, one isolate named GL1^T could highly tolerate Cu²⁺ up to 10 mM, and the isolates could also grow in a wide range of pH (3-7), and temperature (10-40 ℃). Dried biomass of GL1 was able to remove Cu²⁺ effectively up to 90.49% with a maximal biosorption capacity of 18.1 mg/g at pH 6, temperature 30 ℃, and incubation time 60 min. Sequence analysis of rDNA indicated this strain was closely related to Rhodotorula mucilaginosa but with 1.53 and 3.46% nucleotide differences in the D1/D2 domain of the 28S rRNA gene and the ITS1-5.8S rRNA gene-ITS2 region sequence, respectively. Based on phylogenetic tree analysis and the biochemical characteristics, the strain appears to be a novel Rhodotorula species, and the name Rhodotorula aurum sp. nov. is proposed. This study provides us with more information about heavy metal-tolerant yeasts and it may produce a new tool for environmental control and metal recovery operations.

• Journal of Animal Science and Technology
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• v.66 no.5
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• pp.876-890
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• 2024

A balanced intestinal microbiome controls intestinal bacterial diseases, helps regulate immunity, and digests and utilizes nutrients, ultimately having a positive effect on the productivity of industrial animals. Yeasts help in the digestion process by breaking down indigestible fibers and producing organic acids, vitamins, and minerals. In particular, polysaccharides such as beta-glucan and mannan-oligosaccharides, which are present in the cell wall of yeast, inhibit the adhesion of pathogens to the surface of the gastrointestinal tract and increase resistance to disease to help maintain and improve intestinal health. Among the yeast additives used in animal feed, Saccharomyces cerevisiae is one of the most commonly used probiotics. However, it does not naturally reside in the intestine, so if it is supplied in combination with other species of probiotics that can compensate for it, many benefits and synergies can be expected for pigs in terms of maintaining intestinal health such as supplementing the immune system and improving digestion. A number of previous studies have demonstrated that dietary complex probiotic supplementation has growth-promoting effects in pigs, suggesting that multiple strains of probiotics may be more effective than single strain probiotics due to their additive and synergistic effects. In practice, however, the effects of complex probiotics are not always consistent, and can be influenced by a variety of factors. Therefore, this review comprehensively examines and discusses the literature related to the effects of complex probiotics using Saccharomyces cerevisiae in pig production.

• Food Science and Preservation
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• v.11 no.3
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• pp.400-404
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• 2004

This study was conducted to find the antimicrobial activity of garlic extracts by various processing methods(boiled, pan fried, microwave heated, pickled). Ethanol and water extracts from garlic sample were prepared and antimicrobial activities were determined against 10 microoganisms ; food borne pathogens, food poisoning microoganisms, food-related bacteria and yeasts. The ethanol extracts from the fresh and pickled garlic showed antimicrobial activities for test microoganisms, except lactic acid bacteria and yeast. However, the antimicrobial activities were decreased by heat treatment. The minimum inhibitory concentration(MIC) of the fresh garlic extracts was determined to 0.1 mg/mL against an gram positive bacterium and 0.5 mg/mL against an gram negative bacterium. The antimicrobial activities of the ethanol extracts were affected by heating methods and not by pHs.

• Food Science and Preservation
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• v.12 no.3
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• pp.257-262
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• 2005

To develop natural food preservatives, ethanol and water extracts were prepared from chestnut. Antimicrobial activities were examined about 10 microoganisms which were food-borne pathogens and food-poisoning microoganisms, food-related bacteria and yeasts. Ethanol extract exhibited the antimicrobial activity for the microoganisms tested, except lactic acid bacteria and yeast Especially, minimum inhibitory concentrations(MIC) of the ethanol extracts were determined as 0.5 mg/mL in chestnut leaf and 1.0 mg/mL in chestnut balk against bacteria. Antimicrobial activity of the ethanol extracts was not destroyed by the heating at $121^{\circ}C$ for 15 min, and not affected by pH $3{\sim}9$. The ethanol, extract of chestnut exhibiting the high antimicrobial activities was fractionated in the other of diethylether and butanol fractions. The highest antimicrobial activity against bacteria was shown in the ethanol fraction.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.6
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• pp.1008-1013
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• 1994

To develope naatural food preservatives, ethanol and water extracts were prepared from the leaf mustard (Brassica juncea Coss.) and antimicrobial activities were examined against 15 microorganisms which were food borne pathogens and/or food poisioning microorganisms and food-related bacteria and yeasts. Ethanol extract exhibited anitmicrobial activities for the microorganism tested, especially, minimum inhibitory concnetrations exhibited antimicrobial activities for the microorganism tested, especially, minimum inhibitory concentrations (MIC) for Bacillus subtilis and Bacillus natto were as low as 10mg/ml. MIC of water extract was 40-60mg/ml for bacteria and yeast. The ethanol extract showed the antimicrobial activity by 3~6 times higher than the water extract. Antimicrobial activity of the ethanol extract was not destroyed by the heating at $121^{\circ}C$ for 15 min and not affected by pH.

• Applied Biological Chemistry
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• v.39 no.1
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• pp.9-15
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• 1996

To improve the quality of Choungju. a kind of rice wine, two different types of koji were prepared and compared : one from wheat bran with Aspergillus usamii mut. shirousami Y-79 and the other from rice with A. oryzae, and yeast strains from cereal wine mashes were newly isolated and applied for the brewing method. Levels of the related enzymes such as glucoamylase, ${\alpha}-amylase$ and acid protease in the wheat bran koji were higher than those in the rice koji, whereas vice versa in the case of acid carboxypeptidase. An amount of $2{\sim}3%$ wheat bran koji to the weight of total rice was adequate for saccharification of the mash and resulted in improved duality of the fermented mash, accompanied by decrease in koji ordor and amino acidity. When the solution of wheat bran koji and the isolated yeast strains were employed, the better Choungju taste was obtained in comparison with those fermented with Japanese sake yeasts, the strain K-7 and 9, due to the lower content of organic acids especially succinic acid. The amino acidity of the fermented mash was able to be controlled to some extent, when the rico types of koji and the isolated strains were employed, by changing the ratio of the two koji types. However, the application of the rice koji with the isolated strains was not desirable for the brewing process because organic acids were produced in excess and ethanol fermentation was retarded.

• KSBB Journal
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• v.15 no.2
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• pp.174-180
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• 2000

Pichia pastoris and Hansenula polymorpha, the methylotrophic yeasts have been widely used as a host for the production of e eudaryotic proteins due to the advantages related to their inherited characters. This paper describes the method to enhance t the productivity of recombinant proteins by P. pastoris and H. po$\psi$morpha. In the production of recombinant proteins using a f fed batch fermentation system, the effects of specific growth rate on the specific expression rate of re$\infty$mbinant proteins w were studied. In both species, the expression system of recombinant proteins using the fed batch fermentation was optimezed.

• Korean Journal of Food Science and Technology
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• v.17 no.6
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• pp.474-481
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• 1985

Radurization effects on fried fish meat paste with Co-60 gamma irradiation at 0-5 kGy and physicochemical aspects of the stored samples at low ($3{\pm}1^{\circ}C$, LT) and room ($10-20^{\circ}C$, RT) temperatures were investigated. The initial microbial loads of the samples were $2.2{\times}10^3/g$ in total bacterial count, $2.8{\times}10^2/g$ in yeasts & molds, and $1.0{\times}10^2/g$ in coliform group, respectively. An irradiation dose of more than 3 kGy was shown to be effective for the radurization of stored samples and there is no apparent difference between air and vacuum packaging groups. The chemical components related to the quality underwent similar changes in the nonirradiated and irradiated groups; however, as the storage time was prolonged the quality of nonirradiated samples rapidly deteriorated. Textural parameters of the samples were little affected by the applied doses, and sensory evaluations showed that 3 kGy irradiation was the optimum dose level to extend the shelf-life of fried fish meat paste up to 2 times at RT and 3 to 4 times at LT, respectively compared with the nonirradiated control.

• Food Science and Preservation
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• v.19 no.2
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• pp.308-314
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• 2012

Two hundred and twenty three yeast strains were randomly isolated from Korean traditional $nuruk$. Among them, six urease producing yeast strains (designated JJA, JJB, JJ22, SHA, SHC and SH10) were selected on the Christensen urea agar plates. They showed the same pattern in the PCR-RFLP analysis of the ITS I-5.8S-ITS II region digested with $Hae$III and $HinF$1 restriction endonucleases. Its DNA sequences showed 100% (strains SHA, SHC and SH10) and 99.8% (strains JJA, JJB and JJ22) identity with those of $Issatchenkia$ $orientalis$ type strain ATCC 24210. Phylogenetic analysis resulted in that all the strains were closely related to $I.$ $orientalis$. Two representative strains, JJ22 and SH10, showing the highest urease activities were selected for further characterization. Their morphological, physiological and biochemical characteristics were also the same as $I.$ $orientalis$. Therefore, both the two strains were identified as $I.$ $orientalis$. They could grow at a wide range of temperature between $20-40^{\circ}C$ as well as pH between 2.0 and 10.0. However, a higher level urease activity were obtained at acidic pH than that at alkalic pH. The maximal level of urease activity was obtained at $30^{\circ}C$ (strain SH10) or $35^{\circ}C$ (strain JJ22) and in a liquid medium adjusted to the initial pH 5.0.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.4
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• pp.692-696
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• 2001

To develop natural food preservatives, ethanol and water extracts were prepared from the coriander (Coriandrum sativum L.) and antimicrobial activities were examined against 10 microorganisms which were food borne pathogens and/or food poisoning microorganisms and food-related bacteria and yeasts. Ethanol extract exhibited antimicrobial activities for the microorganisms tested, but not on lactic acid bacteria and yeast. Especially, minimum inhibitory concentrations (MIC) for Bacillus subtilis and Bacillus cereus were as low as 0.25mg/mL. antimicrobial activity of the ethanol extract was not destroyed by the heating at 121$^{\circ}C$ for 15min and not affected by pH. The ethanol extract of coriander exhibiting high antimicrobial activities was fractionated in the order of hexane, chloroform, ethylacetate and butanol fractions to test antimicrobial activity. The highest antimicrobial activity adjust bacteria tested was found in the ethylacetate fraction.