• The Korean Journal of Mycology
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• v.47 no.3
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• pp.249-258
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• 2019

The goal of this study was to isolate and characterize the wild yeast strains in the soils of Hajodae and Gyungpodae Beaches, Gyungpo Lake in Kangwon-do, Korea and evaluate their anti-demential and tyrosinase inhibitory activities. Among the 27 yeast strains isolated from 30 soil samples from Hajodae Beach, Cyberlindnera culbertsonii HJ31-1, Dothichiza pithyophila HJ22-4, Metschnikowia bicuspidata HJ16-1, and Sakaguchia cladiensis HJ14-1 were recorded for the first time in Korea. Additionally, six of the 55 wild yeast strains isolated from 45 soil samples from Gyungpodae Beach and Gyungpo Lake had not previously been detected in Korea, such as Aureobasidium melanogenum JR3-1. The microbiological characteristics and anti-demential and tyrosinase inhibitory activities of these previously unrecorded yeasts were investigated. Almost all of them were oval-shaped and had ascospores except for Dothichiza pithyophila HJ22-4, Diutina siamensis JR37-5, and Canadida gelsemii DC 35-1. Furthermore, they were all sugar-tolerant and able to grow in 20% glucose-containing YPD broth, except for Cyberlindnera culbertsonii HJ31-1. Diutina siamensis JR37-5 had the highest tyrosinase inhibitory activity (30.9%).

• The Korean Journal of Mycology
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• v.39 no.3
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• pp.205-212
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• 2011

Phenylalanine ammonia-lyase (PAL) from the maize pathogen Ustilago maydis was analysed immunologically to obtain insights into the structural relationships between plant PAL and fungal PAL and between PAL and histidine ammonia-lyase (HAL). Cross-reactivity was found among all the PAL proteins from different species tested, using antibodies raised against both plant and fungal PALs. Both anti-Alfalfa and anti-popular PAL antibodies strongly recognized plant PALs but only weakly recognized fungal PALs. Antibodies raised against U. maydis PAL only weakly recognized the Rhodotorula glutinis yeast PAL. The anti-U. maydis PAL antibodies showed low affinity for the plant PALs but they bound strongly to Pseudomonas bacterial HAL. Significant cross-reactivity between the two plant PAL antibodies and the bacterial HAL was also observed. Both the anti-Ustilago PAL and the anti-poplar PAL antibodies displayed similar enzyme inhibition patterns, including moderate inhibition of bacterial HAL activity. However, the bacterial HAL antibody inhibited only Ustilago PAL. The PAL and HAL antibodies tested showed no inhibition against yeast PAL. This is first report on the immunological relationships between PAL and HAL.

• Microbiology and Biotechnology Letters
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• v.46 no.4
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• pp.403-415
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• 2018

The aims of this novel work were to determine the microbial strains and exopolysaccharide (EPS) producers in water kefir from Nakhon Ratchasima Province, Thailand. Thirty-three microbial strains were identified using 16S rRNA gene analysis consisting of 18 bacterial strains, as 9 strains of acetic acid bacteria (AAB), 9 strains of lactic acid bacteria (LAB), and 15 yeast strains. All bacteria were able to produce EPS with a diverse appearance on agar media containing different sugars at a concentration of 8%. Culture supernatants from AAB and LAB showed 31-64% 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity with the highest antioxidant activity of 64% from Acetobacter pasteurianus WS3 and WS6. Crude EPS from A. pasteurianus WS3 displayed the highest ferric reducing antioxidant power at 280 mM $FeSO_4/g$ EPS, greatest anti-tyrosinase activity at 20.35%, and highest EPS production of 1,505 mg EPS/L from 8% sucrose. These microbes offer beneficial health implications and their EPSs can be used as food additives and cosmetic ingredients.

• Journal of Microbiology and Biotechnology
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• v.28 no.5
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• pp.697-706
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• 2018

Lactobacillus pentosus K1-23 was selected from among 25 lactic acid bacterial strains owing to its high inhibitory activity against several pathogenic bacteria, including Escherichia coli, Salmonella typhimurium, S. gallinarum, Staphylococcus aureus, Pseudomonas aeruginosa, Clostridium perfringens, and Listeria monocytogenes. Additionally, among 13 strains of Aureobasidium spp., A. pullulans NRRL 58012 was shown to produce the highest amount of ${\beta}$-glucan ($15.45{\pm}0.07%$) and was selected. Next, the optimal conditions for a solid-phase mixed culture with these two different microorganisms (one bacterium and one yeast) were determined. The optimal inoculum sizes for L. pentosus and A. pullulans were 1% and 5%, respectively. The appropriate inoculation time for L. pentosus K1-23 was 3 days after the inoculation of A. pullulans to initiate fermentation. The addition of 0.5% corn steep powder and 0.1% $FeSO_4$ to the basal medium resulted in the increased production of lactic acid bacterial cells and ${\beta}$-glucan. The following optimal conditions for solid-phase mixed culture were also statistically determined by using the response surface method: $37.84^{\circ}C$, pH 5.25, moisture content of 60.82%, and culture time of 6.08 days for L. pentosus; and $24.11^{\circ}C$, pH 5.65, moisture content of 60.08%, and culture time of 5.71 days for A. pullulans. Using the predicted optimal conditions, the experimental production values of L. pentosus cells and ${\beta}$-glucan were $3.15{\pm}0.10{\times}10^8CFU/g$ and $13.41{\pm}0.04%$, respectively. This mixed culture may function as a highly efficient antibiotic substitute based on the combined action of its anti-pathogenic bacterial and immune-enhancing activities.

• Molecules and Cells
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• v.26 no.1
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• pp.93-99
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• 2008

Transcriptional silencing is regulated by promoter methylation and histone modifications such as methylation and acetylation. We constructed a Schizosaccaromyces pombe reporter strain, KCT120a, to identify modifiers of transcriptional silencing, by inserting the $ura4^+$ gene into a heterochromatic telomere region. Two compounds inhibited the activity of histone deacetylases, induced acetylation of histone H3 and caused apoptotic cell death in HeLa cells. Expression of gelsolin and $p21^{waf1/cip1}$ also increased, as it does in response to HDAC inhibitors such as TSA. Therefore, these compounds appear to be potent inhibitors of HDACs, and hence potential anti-cancer drugs. Our observations suggest that a yeast cell-based assay system for transcriptional silencing may be useful for identifying histone deacetylase inhibitors and other agents affecting chromatin remodeling.

• Microbiology and Biotechnology Letters
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• v.35 no.2
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• pp.118-127
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• 2007

Germanium-fortified yeast (GY) is a organic germanium-fortified yeast with potent immune modulating activities including anti-inflammatory effect. Through cell line studies, we observed that GY can modulate the diverse immune activity but little evidence was provided on the mechanism of GY in modulating immune activities in other higher animals. In this study, we investigated the effect of GY on modulation of immune function in mice. GY was administered in normal mice or tumor-bearing mice and then effect of GY on modulation of host immune system was analyzed by using ex vivo isolated macrophages, B cells, NK cells. Admistration of GY in mice induced macrophage activation thereby increased effector function of macrophage such as increased phagocytosis, chemotaxis, adherence, $O_2-release$, NO, $TNF-{\alpha}$ production. In addition, GY administration Increased B lymphocyte activation and plaque forming cells. Furthermore, GY administration increased NK-cell mediated cytotoxicity. Furthermore, GY administration suppressed progression of tumor in mice by increasing $TNF-{\alpha}$ production and effector function of NK cells. Our results showed that GY has a potent immunostimulatory function in vivo mice model. Proper modulation and administration of GY in human could be helpful to maintaining immunological homeostasis by modulating host immune system.

• The Korean Journal of Mycology
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• v.42 no.3
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• pp.201-206
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• 2014

Sixty one yeast strains of 21 species were isolated from wild flowers in Gogunsanyeoldo, including Seonyudo of Jeollabuk-do, Korea, and identified by comparison of nucleotide sequences for PCR-amplified D1/D2 region of 26S rDNA using BLAST. Among them, Cryptococcus sp. including C. aureus SY1-4 were found to be dominant, and Metschnikowia sp. including M. reukaufii SY20-1 and Rhodotnula sp. such as R. ingeniosa SY1-1 were also abundantly isolated. Some physiological functionalities of the culture broth and cell-free extracts from 61 yeast strains were determined. Supernatant from Metschnilowia reukaufii SY44-6 showed anti-gout xanthine oxidase inhibitory activity of 49.6% and whitening tyrosinase inhibitory activity of 38.4%, respectively.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.115-122
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• 2012

Apidaecin Ib had strong antimicrobial activity against several tested Gram-negative bacteria including Escherichia coli, Enterobacter cloacae, and Shigella flexneri (MECs; $0.3-1.5{\mu}g/mL$), but showed no activity against all the tested Gram-positive bacteria including Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus and one yeast, Candida albicans (MECs; > $125{\mu}g/mL$). Interestingly, this peptide showed potent antibacterial activity only against Edwardsiella species (MECs; $0.6-3.6{\mu}g/mL$) among the tested fish pathogenic bacteria through a bacteriostatic process and showed no significant hemolytic activity. Apidaecin Ib took an unordered structure in all environments and also had very weak membrane perturbation activity even at $25{\mu}M$. Anti-Edwardsiella activity of apidaecin Ib is stronger than those of other antimicrobial polypeptides or antibiotics, but its activity is salt-sensitive. These results suggest that apidaecin Ib has Edwardsiella speciesspecific antibacterial activity and could be applied as new preventive or control additives for Edwardsiella species infection in freshwater fish aquaculture.

• BMB Reports
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• v.38 no.3
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• pp.294-299
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• 2005

In this report, we describe the high-yield secretory expression of the recombinant human anti-HBsAg Fab fragment from Pichia pastoris that was achieved by co-integration of the genes encoding the heavy and light chains (both under the control of alcohol oxidase promoter) into the genome of the yeast cells. The fed-batch fermentations were carried out in a 5 L scale. Both chains of the Fab were successfully expressed upon methanol induction. The absorbance ($OD_{600}$) of the broth can reach 350~500 at the end of fed-batch phase. After the induction, the expression level of the recombinant Fab (soluble) reached 420~458 mg/L. The recombinant Fab fragment was purified from the crude culture supernatant by ion exchange chromatography and the purity of the recombinant Fab fragment was over 95%. The affinity activities of the crude fermentation supernatant and the purified Fab were analyzed by indirect ELISA, which showed that the purified recombinant Fab fragment had high affinity activity with hepatitis B surface antigen.

• Microbiology and Biotechnology Letters
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• v.36 no.3
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• pp.215-220
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• 2008

Rahnella aquatilis AY2000 has an unique characteristic which produces an anti-yeast substance (AYS). The AYS of the strain AY2000 was always secreted on agar plate, however, its activity in liquid culture was labile upon storage of the medium. In this paper, cultural conditions of the strain AY2000 for the AYS production were investigated in liquid culture, and minimal inhibitory concentration (MIC) against Saccharomyces cerevisiae was determined for the AYS activity. MIC of the AYS cultured in PYG broth at $^25{\circ}C$ for 24 hr was $23.5{\mu}g/mL$, however, that in MYCS (pH 5.5) broth at the same condition was $15.5{\mu}g/mL$. The activity of the AYS had increased rather in MYCS broth excluded $NH_4$-citrate than in the same broth contained $NH_4$-citrate, and MIC of the AYS produced in MYCS broth without $NH_4$-citrate was $15.5{\mu}g/mL$. When the strain AY2000 was maintained in MYCS broth without $NH_4$-citrate but added $100{\mu}M$ $FeCl_3$, the activity of the AYS had increased and its MIC was $7.8{\mu}g/mL$. MIC of the AYS was $7.8{\mu}g/mL$ after the strain AY2000 was cultured in MYCS broth containing $100{\mu}M$ $FeCl_3$ without $NH_4$-citrate, however, its MIC was $31.3{\mu}g/mL$ after 48-60 hr culture in the same broth.