• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.8
• /
• pp.603-610
• /
• 2009

This research was performed to improve removal efficiency of toluene and methyl ethyl ketone (MEK) using Candida tropicalis, one of the yeast species. An airlift loop bioreactor (ALB) was employed to enhance the capability of mass transfer for toluene and MEK from the gas phase to the liquid, microbial phase. Polymer gel media made from PAC, alginate and PEG was applied for the effective immobilization of the yeast strain on the polymer gel media. The experimental results indicated that the mass transfer coefficient of toluene without polymer gel media was 1.29 $min^{-1}$ at a gas retention time of 15 sec, whereas the KLa value for toluene was increased to 4.07 $min^{-1}$ by adding the media, confirming the enhanced mass transfer of volatile organic compounds between the gas and liquid phases. The removal efficiency of toluene and MEK by using yeast-immobilized polymer gel media in the ALB was greater than 80% at different pollutant loading rates (5, 10, 19 and 37 g/$m^3$/hr for toluene, 4.5, 8.9, 17.8 and 35.1 g/$m^3$/hr for MEK). In addition, an elimination capacity test conducted by changing inlet loading rates stepwise demonstrated that maximum elimination capacities for toluene and MEK were 70.4 and 56.4 g/$m^3$/hr, respectively.

• Journal of Animal Science and Technology
• /
• v.48 no.5
• /
• pp.691-698
• /
• 2006

Three species of the yeast Saccharomyces cerevisiae, Humicola grisea and Candida glabrata were assumed as microbial inoculants for fermentation of rice straw silage. Four types of silage innoculated with three yeasts including control (non-treatment) were opened on day 1, 3, 6, 9, 15 and 20 after ensiling, and analyzed for fermentation status (pH, crude protein, microbial counts) and the microbial population attached with silage texture using SEM (Scanning Electron Microscopy). The results obtained were summarized as fallow; The pH of silage juice was decreased to 4.3 after 6th day of fermentation in the treatments innoculated with yeast, but was not changed at the ranges of 5.47 to 5.67 in control. Crude protein concentration of silage was increased by 38～41% with yeast inoculation compared to control. From SEM observation, it could be confirmed that crude protein concentration of silage was increased by microbial growth and SCP synthesis. The yeast Saccharomyces cerevisiae and Candida glabrata could be used as useful fermenters of rice straw silage.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.27 no.4
• /
• pp.789-799
• /
• 1998

Literatures on microorganisms of traditional Korean nuruk published since 1945 were reviewed in this paper. Traditional Korean nuruk consists of raw barley and various grains. Traditional Korean nuruk consists of unbolied raw barely and various grains. They are ground to paste and moistened, and then naturally inoculated by airborne microorganisms. Therefore, many kinds of microorganisms such as fungi, yeast, and bacteria grwo in nuruk. Since 1945, new 14 species of Aspergillus and 9 species of Penicillium have been identified from traditional Korean nuruk. Total number of fungal species identified so far is now up to 38 species among 12 different genus. Among newly isolated fungal species, Aspergillus penicilloides and Penicillium, expansum showed not only high production rate of acid and amylase but also extreme stability of the enzyme at room temperature for 3 months. As examples of newly isolated yeast species, there are 5 species of Candida, 4 species of Hansenula, 1 species of Pichia and 1 species of Schizosaccharomyces. Total number of yeast species isolated so far is up to 18 species from different 8 genus. Newly isolated bacteria, were Bacillus pumilus, Lactobacillus casei and Leuconostoc mesenteroides.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.8
• /
• pp.803-809
• /
• 2009

Recent evidence has revealed the occurrence of an apoptotic phenotype in Candida albicans that is inducible with environmental stresses such as acetic acid, hydrogen peroxide, and amphotericin B. In the present study, we found that the Chinese herbal medicine Baicalein (BE), which was one of the skullcapflavones, can induce apoptosis in C. albicans. The apoptotic effects of BE were detected by flow cytometry using Annexin V-FITC and DAPI, and it was confirmed by transmission electron microscopy analysis. After exposure to 4 ${\mu}g$/ml BE for 12 h, about 10% of C. albicans cells were apoptotic. Both the increasing intracellular levels of reactive oxygen species (ROS) and upregulation of some redox-related genes (CAP1, SOD2, TRR1) were observed. Furthermore, we compared the survivals of CAP1 deleted, wild-type, and overexpressed strains and found that Cap1p attenuated BE-initiated cell death, which was coherent with a higher mRNA level of the CAP1 gene. In addition, the mitochondrial membrane potential of C. albicans cells changed significantly (p<0.001) upon BE treatment compared with control. Taken together, our results indicated that BE treatment induced apoptosis in C. albicans cells, and the apoptosis was associated with the breakdown of mitochondrial membrane potential.

• Journal of Microbiology and Biotechnology
• /
• v.24 no.1
• /
• pp.87-96
• /
• 2014

In the present study, a yeast species isolated from CETP, Vellore, Tamilnadu was identified as Cryptococcus sp. VITGBN2 based on molecular techniques and was found to be a potent producer of acidic diacetate sophorolipid in mineral salt media containing vegetable oil as additional carbon source. The chemical structure of the purified biosurfactant was identified as acidic diacetate sophorolipid through GC-MS analysis. This sophorolipid was used as a stabilizer for synthesis of zinc oxide nanoparticles (ZON). The formation of biofunctionalized ZON was characterized using UV-visible spectroscopy, XRD, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy. The antimicrobial activities of naked ZON and sophorolipid functionalized ZON were tested based on the diameter of inhibition zone in agar well diffusion assay, microbial growth rate determination, protein leakage analysis, and lactate dehydrogenase assay. Bacterial pathogen Salmonella enterica and fungal pathogen Candida albicans showed more sensitivity to sophorolipid biofunctionalized ZON compared with naked ZON. Among the two pathogens, S. enterica showed higher sensitivity towards sophorolipid biofunctionalized ZON. SEM analysis showed that cell damage occurred through cell elongation in the case of S. enterica, whereas cell rupture was found to occur predominantly in the case of C. albicans. This is the first report on the dual role of yeast-mediated sophorolipid used as a biostabilizer for ZON synthesis as well as a novel functionalizing agent showing antimicrobial property.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.11
• /
• pp.1891-1907
• /
• 2016

Yeasts that are present in marine environments have evolved to survive hostile environments that are characterized by high exogenous salt content, high concentrations of inhibitory compounds, and low soluble carbon and nitrogen levels. Therefore, yeasts isolated from marine environments could have interesting characteristics for industrial applications. However, the application of marine yeast in research or industry is currently very limited owing to the lack of a suitable isolation method. Current methods for isolation suffer from fungal interference and/or low number of yeast isolates. In this paper, an efficient and non-laborious isolation method has been developed and successfully isolated large numbers of yeasts without bacterial or fungal growth. The new method includes a three-cycle enrichment step followed by an isolation step and a confirmation step. Using this method, 116 marine yeast strains were isolated from 14 marine samples collected in the UK, Egypt, and the USA. These strains were further evaluated for the utilization of fermentable sugars (glucose, xylose, mannitol, and galactose) using a phenotypic microarray assay. Seventeen strains with higher sugar utilization capacity than the reference terrestrial yeast Saccharomyces cerevisiae NCYC 2592 were selected for identification by sequencing of the ITS and D1/D2 domains. These strains belonged to six species: S. cerevisiae, Candida tropicalis, Candida viswanathii, Wickerhamomyces anomalus, Candida glabrata, and Pichia kudriavzevii. The ability of these strains for improved sugar utilization using seawater-based media was confirmed and, therefore, they could potentially be utilized in fermentations using marine biomass in seawater media, particularly for the production of bioethanol and other biochemical products.

• Korean Journal of Microbiology
• /
• v.22 no.1
• /
• pp.49-56
• /
• 1984

Formation and regeneration of protoplasts by Novozym 234 from Kluyveromyces fragilis N100 and Candida pseudotropicalis CBS607 were studied. This enzyme was more effective on cells grown at exponential phase than those at stationary one to convert intact cells into protoplasts. As osmotic stabilizer, ammonium sulphate was suitable for not only protoplast formation but also regeneration in K. fragilis as well as in C. pseudotropicalis. Optimal enzyme concentration was 3mg per ml in K. fragilis and 1~3mg per ml in C. pseudotropicalis, respectively. After the exposure of K. fragilis cells to 3mg per ml of enzyme for 3hr at 30$^{\circ}C$ , approximately 95% of protoplast formation of all observed cells was obgained, while about 100% from C. pseudotropicalis under the same condition was produced. The regeneration frequency of protoplasts by this enzyme was much lower than that by snail enzyme(Glusulase) although Novozym 234 converted cells from above two species into protoplasts free of cell debris effectively, compared with Glusulase. Novozym 234 appears to be suitable for subcellular fractionation to obtain nuclei or other organelles rather than protoplast regeneration.

• The Korean Journal of Mycology
• /
• v.21 no.1
• /
• pp.77-84
• /
• 1993

Out of 210 tinea capitis cases studies, 16 were negative when examined with KOH, among the remaining 194 cases, 123 were males (63.4%) and 71 were females (36.6%) and the age of incidence ranged between 7 and 15 years. Microsporum was the main causal agent being identified in 82 cases (42.3%) and was represented by 5 species among which M. canis was common in Egypt (55 cases, 28.4%). Trichophyton constituted 32% and was represented by 8 species among which T. violaceum was the most common (24.2% of total cases). Candida were isolated from 3.6% of total cases. The 47 species and twenty-five genera from nondermatophyte-cyclohexamide resistant fungi were recovered from the diseased skin tissue. Penicillium and Aspergillus were the most abundant followed by Scopulariopsis, Alternaria, Thermoascus, Chrysosporium and Cladosporium. Studies of the air-borne fungi in-door the hospital wards revealed the occurrence of 57 species belonging to 28 genera, among which Aspergillus flavus, Penicillium chrysogenum, p. corylophilum, A. niger, Tritirachium rosum and Alternaria alternata were the most common. Results of the out-door experiments were basically similar to those of the in-door experiments.

• 한국균학회소식:학술대회논문집
• /
• 2014.10a
• /
• pp.44-44
• /
• 2014

Yeasts were isolated from wild flowers of some islands and mountains such as Jeju-do, Ulleungdo, Yokjido, Seonyudo and Gyejoksan, Oseosan, Beakamsan and Deogyusan in Korea and were identified by comparison of nucleotide sequences for PCR-amplified D1/D2 region of 26S rDNA or internal transcribed pacer(ITS) 1 and 2 including 5.8S rDNA using BLAST. Seventy two yeast strains of two hundred eighty nine species were isolated from wild flowers in islands and mountains, Korea. Among them, Cryptococcus species were isolated the most dominantly, and Metschnikowia reukaufii were also isolated thirty species, 10.3% of total strains. Twenty-three species including Cryptococcus aureus were overlapped between yeast strains of the islands and mountains. Some physiological functionality of the culture broth and cell-free extracts from two hundred eighty nine yeast strains were determined. The supernatant of Candida sp. 78-J-2 showed antioxidant activity of 22.5%, and supernatant of Metschnilowia reukaufii SY44-6 showed anti-gout xanthine oxidase inhibitory activity of 49.6% and whitening tyrosinase inhibitory activity of 38.4%, respectively.

• Natural Product Sciences
• /
• v.13 no.3
• /
• pp.258-262
• /
• 2007

The antifungal activity of the essential oil fraction from Thymus magus, and its major component thymol, against Candida albicans was investigated in vitro and in vivo. The combined effects of the oils and clotrimazole, a commonly used antifungal drug for treatment of external candidiasis, were evaluated in this study. In experimental vaginal candidiasis the essential oil fraction of T. magnus resulted in relatively milder inhibition of fungal growth following the inoculation of test mice compared to clotrimazole. However, new fungal growth was not detected up to 12 days after cessation of treatment. In contrast, in a similar experiment using clotrimazole, C. albicans was detected in the $12^{th}$ day post-treatment with the sample. This result indicates that T. magnus oil could be a promising drug to control vaginal candidiasis. In checkerboard titer tests, the combination of clotrimazole with the essential oil fraction of T. magus or T. quinquecostatus resulted in significant synergism, with FIC indices between 0.14 and 0.27 against C. albicans, while clotrimazole combined with thymol, the major component of these oils, produced only an additive effect, with FIC indices ranging between 0.50 and 1.00. Thus, the prominent synergistic effects of clotrimazole combined with T. magus essential oil indicate that these compounds may be an effective treatment for C. albicans infections.