• The Korean Journal of Mycology
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• v.51 no.4
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• pp.287-306
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• 2023

According to our previous study, 500 species of yeast exist in Korea, including nine variants comprising 142 genera and 48 classes in two phyla. Additionally, 4,483 fungal species have been documented at the National Institute of Biological Resources (NIBR). However, despite the industrial use of several yeasts, only 173 species formed part of the National Species List of Korea (NSLK) as of December 2021, mainly due to the lack of taxonomic descriptions. This study aimed to investigate the taxonomy of seven newly isolated yeast species (Hyphopichia burtonii, Starmerella sorbosivorans, Cyberlindnera mycetangii, Cutaneotrichosporon oleaginosum, Nakazawaea ernobii, Pichia kudriavzevii, and Schizosaccharomyces japonicus) for inclusion in the NSLK. The strains were clustered for the phylogenetic analysis of fungal rDNA (D1/D2-26S) sequences. This study provides descriptions of their cell morphology and physiological characteristics, the results of which confirm the indigenous origin of these seven species in Korea and recommend their inclusion in the NSLK.

• Parasites, Hosts and Diseases
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• v.61 no.3
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• pp.317-324
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• 2023

Standard- and large-sized eggs of Trichuris trichiura were found in the feces of schoolchildren in Yangon, Myanmar during epidemiological surveys and mass deworming with albendazole in 2017-2019. The standard-sized eggs were identified as those of T. trichiura, but it was necessary to exclude the possibility of the large-sized eggs belonging to Trichuris vulpis, a dog whipworm. We conducted morphological and molecular studies to determine the species of the 2 types of Trichuris eggs. Individual eggs of both sizes were isolated from Kato-Katz fecal smears (n=20) and mechanically destroyed using a 23G injection needle. Nuclear DNA was extracted, and the 18S rRNA region was sequenced in 15 standard-sized eggs and 15 large-sized eggs. The average size of standard-sized eggs (T. trichiura) was 55.2×26.1 ㎛ (range: 51.7-57.6×21.3-28.0 ㎛; n=97), whereas the size of large-sized eggs was 69.3×32.0 ㎛ (range: 65.1-76.4×30.1-34.5 ㎛; n=20), slightly smaller than the known size of T. vulpis. Regarding standard-sized eggs, the 18S rRNA nucleotide sequences exhibited 100% homology with T. trichiura deposited in GenBank and 88.6-90.5% homology with T. vulpis. Regarding large-sized eggs, the nucleotide sequences showed 99.8-100% homology with T. trichiura in GenBank and 89.6-90.7% homology with T. vulpis. Both standard- and large-sized eggs of Trichuris spp. found in Myanmar schoolchildren during 2017-2019 were morphologically and molecularly confirmed to belong to T. trichiura. The conversion of eggs from smaller to large sizes might be due to anthelmintic treatments with albendazole.

• Microbiology and Biotechnology Letters
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• v.33 no.2
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• pp.148-153
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• 2005

Malaria is a re-emerging infectious disease that is spreading to areas where it had been eradicated, such as Eastern Europe and Central Asia. To avoid the mortality from malaria, early detection of the parasite is a very important issue. The peripheral blood smear has been the gold standard method for the diagnosis of malaria infection. Recently, several other methods have been introduced for quantitative detection of malaria parasites. Real time PCR that employs fluorescent labels to enable the continuous monitoring of PCR product formation throughout the reaction has recently been used to detect several human malaria parasites. 18S rRNA sequences from malaria parasites have been amplified using Taqman real time PCR assay. Here, a SYBR Green-based real time quantitative PCR assay for the detection of malaria parasite-especially, Plasmodium vivax - was applied for the evaluation of 26 blood samples from Korean malaria patients. Even though SYBR Green-based real time PCR is easier and cheaper than Taqman-based assay, SYBR Green-based assay cannot be used because 18S rRNA cannot be specifically amplified using 1 primer set. Therefore, we used DBP gene sequences from Plasmodium vivax, which is specific for the SYBR Green based assays. We amplified the DBP gene from the 26 blood samples of malaria patients using SYBR Green based assay and obtained the copy numbers of DBP genes for each sample. Also, we selected optimal reference gene between ACTB and B2M using real time assay to get the stable genes regardless of Malaria titer. Using selected ACTB reference genes, we successfully converted the copy numbers from samples into titer, ${\sharp}$ of parasites per microliter. Using the resultant titer from DBP based SYBER Green assay with ACTB reference gene, we compared the results from our study with the titer from Taqman-based assay. We found that our results showed identical tendency with the results of 18S rRNA Taqman assay, especially in lower titer range. Thus, our DBP gene-utilized real time assay can detect Plasmodium vivax in Korean patient group semi-quantitatively and easily.

• Journal of Microbiology and Biotechnology
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• v.22 no.7
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• pp.960-966
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• 2012

The diversity and composition of yeast populations may greatly impact wine quality. This study investigated the yeast microbiota in two different types of wine fermentations: direct inoculation of a commercial starter versus pied de cuve method at an industrial scale. The pied de cuve fermentation entailed growth of the commercial inoculum used in the direct inoculation fermentation for further inoculation of additional fermentations. Yeast isolates were collected from different stages of wine fermentation and identified to the species level using Wallersterin Laboratory nutrient (WLN) agar followed by analysis of the 26S rDNA D1/D2 domain. Genetic characteristics of the Saccharomyces cerevisiae strains were assessed by a rapid PCR-based method, relying on the amplification of interdelta sequences. A total of 412 yeast colonies were obtained from all fermentations and eight different WL morphotypes were observed. Non-Saccharomyces yeast mainly appeared in the grape must and at the early stages of wine fermentation. S. cerevisiae was the dominant yeast species using both fermentation techniques. Seven distinguishing interdelta sequence patterns were found among S. cerevisiae strains, and the inoculated commercial starter, AWRI 796, dominated all stages in both direct inoculation and pied de cuve fermentations. This study revealed that S. cerevisiae was the dominant species and an inoculated starter could dominate fermentations with the pied de cuve method under controlled conditions.

• The Korean Journal of Mycology
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• v.43 no.3
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• pp.137-141
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• 2015

This study focused on isolation of wild yeasts from natural flowers and elucidation of yeast diversity. Wild yeasts were isolated from various flowers collected from mountains on the islands including Jejudo, Ulleungdo, Yokjido, and Seonyudo as well as inlands including Gyejoksan, Oseosan, Beakamsan, and Deogyusan in Korea. Isolated yeasts were identified by comparison of nucleotide sequences for polymerrase chain reaction-amplified D1/D2 region of 26S rDNA or internal transcribed spacer 1 and 2 including 5.8S rDNA using BLAST. 289 strains belonging to 134 yeast species were isolated. Cryptococcus genus strains were the most frequently isolated species among the identified yeasts. Metschnikowia reukaufii was also frequently isolated. Twenty three species including Cryptococcus aureus were overlapped between those of mountains on islands and inland. Physiological functionalities such as antioxidant activity, xanthine oxidase inhibitory activity, and tyrosinase inhibitory activity for the 289 identified yeast strains were investigated using their supernatant and cell-free extracts. The supernatants of Candida sp. 78-J-2 and Metschnikowia reukaufii SY44-6 showed antioxidant activity of 22.5%, and anti-gout xanthine oxidase inhibitory activity of 49.6%, respectively.

• Korean journal of applied entomology
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• v.53 no.1
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• pp.15-26
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• 2014

The black soldier fly, Hermetia illucens, larvae may depend on indigenous bacteria in the intestine to feed and digest diverse food sources. To prove this hypothesis, we isolated and identified the intestinal bacteria of the black soldier fly for their digestive and antimicrobial abilities. The last instar larvae had long digestive tracts, which were about seven times longer than its body length. An individual of H. illucens larvae possessed a total of $5.0{\pm}10^6$ bacteria in the whole intestine, of which more than 98% bacteria were located in the hindgut. Three different bacterial isolates cultured on nutrient agar (NA) medium were detected in the intestine and identified as Morganella morganii, Providencia rettgeri and Bacillus halodurans by Biolog microbial identification system. Analysis of 16S rDNA sequences of the intestinal bacteria detected the additional bacteria of Proteus mirabilis, Providencia alcalifaciens, and Providencia sp. These intestinal bacteria cultured on NA medium exhibited high resistance to 4 antibiotics and inhibited growth of other microbes which are mainly plant pathogens. Also, these bacteria exhibited catalytic activities to degrade cellulose, lipid, proteins, and carbohydrates. These results suggest that H. illucens larvae possess intestinal bacteria that may play crucial roles in their digestive physiology.

• Microbiology and Biotechnology Letters
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• v.43 no.1
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• pp.56-64
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• 2015

It has been known for some time to the wine industry that non-Saccharomyces yeasts play an important role in increasing volatile components through the secretion of extracellular enzymes. The objective of this study was to investigate what types of enzymes are produced by 1,007 non-Saccharomyces yeast strains isolated from Korean fermented foods. Among 1,007 yeast strains, the 566, 45 and 401 strains displayed β-glucosidase, glucanase and protease activity, respectively. In addition, the 563 and 610 strains possessed tolerances against cerulenin and TFL, and the 307 strain was tolerant to 15% ethanol. Yeasts producing harmful biogenic amines and hydrogen sulfide were excluded from further study, and eventually 12 yeast strains belonging to the genera Wickerhamomyces, Hanseniaspora, Pichia, Saccharomyces were identified, based on the 26S rRNA gene sequences. Among the 12 strains, the 9 and 5 strains possessed glucose and ethanol tolerance, respectively. Yeasts belonging to the genus Saccharomyces produced more than 8% alcohol, but non-Saccharomyces yeasts produced only 3% alcohol.

• Molecules and Cells
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• v.26 no.6
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• pp.536-547
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• 2008

Anthocyanidin synthase (ANS, leucoanthocyanidin oxygenase), a 2-oxoglutarate iron-dependent oxygenase, catalyzed the penultimate step in the biosynthesis of the anthocyanin class of flavonoids, from the colorless leucoanthocyanidins to the colored anthocyanidins. The full-length cDNA and genomic DNA sequences of ANS gene (designated as GbANS) were isolated from Ginkgo biloba for the first time. The full-length cDNA of GbANS contained a 1062-bp open reading frame (ORF) encoding a 354-amino-acid protein. The genomic DNA analysis showed that GbANS gene had three exons and two introns. The deduced GbANS protein showed high identities to other plant ANSs. The conserved amino acids (H-X-D) ligating ferrous iron and residues (R-X-S) participating in 2-oxoglutarate binding were found in GbANS at the similar positions like other ANSs. Southern blot analysis indicated that GbANS belonged to a multi-gene family. The expression analysis by real-time PCR showed that GbANS expressed in a tissue-specific manner in G. biloba. GbANS was also found to be up-regulated by all of the six tested abiotic stresses, UV-B, abscisic acid, sucrose, salicylic acid, cold and ethylene, consistent with the promoter region analysis of GbANS. The recombinant protein was successfully expressed in E. coli strain with pET-28a vector. The in vitro enzyme activity assay by HPLC indicated that recombinant GbANS protein could catalyze the formation the cyanidin from leucocyanidin and conversion of dihydroquercetin to quercetin, suggesting GbANS is a bifunctional enzyme within the anthocyanidin and flavonol biosynthetic pathway.

• The Korean Journal of Mycology
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• v.45 no.4
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• pp.259-269
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• 2017

In order to investigate the diversity of yeasts from major rivers (the Daejeoncheon, Gapcheon and Yudeungcheon) located in Daejeon city, we isolated wild yeasts by plating diluents of samples collected during the summer and winter of 2016 onto yeast extract-peptone-dextrose (YPD) medium, then identified them using Basic Local Alignment Search Tool (BLAST) analysis to compare the nucleotide sequences of the PCR amplicons for the D1/D2 domain of 26S rDNA. In total, we isolated 191 yeast strains belonging to 104 species from 148 soil or water samples from the rivers and their junctions. Candida spp. (45 strains) including Candida tropicalis (22 strains) were the most abundantly isolated strains from the Daejeoncheon. Candida spp. (16 strains) including Candida vartiovaarae (8 strains) and Candida spp. (18 strains) such as Candida sake (4 strains) were also the dominant isolates from the Gapcheon and Yudeungcheon, respectively. In conclusion, Candida spp. and Cryptococcus spp. were the most dominant strains, corresponding to 42% and 7% of the 191 yeast strains isolated in this study, respectively.

• Parasites, Hosts and Diseases
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• v.34 no.2
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• pp.135-142
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• 1996

Antigenic domain of jai or surface protein (p30) of Toxoplosmc Sondii was analyzed after polymerase chain reaction (PCR) of its gene fragments. Hydrophilic or hydrophobic moiety of amino acid sequences were expressed as glutathione S-transferase (G57) fusion proteins. Fragments of p30 gene were as follows: 737, total p30 open reading frame (ORF) ; S28, total ORF excluding N-terminal signal sequence and C-terminal hydrophobic sequence; Al9, N-terminal 2/3 parts of A28; A19, N-terminal 2/3 of S28; P9, C-terminal 2/3 part of S28; Z9. middle 1/3 of S28; and 29, C-terminal 1/3 of S28. respectively. Primer of each fragment was synthesized to include clamp sequence of EcoR I restriction site. PCR amplified DNA was inserted info GST (26 kDa) expression vector, PGEX-47-1 to transform into Escheri,hia coei (.JM105 strain). G57 fusion proteins were expressed with IPTG induction as 63. 54, 45, 45, 35, 36. and 35 kDa proteins measured by SDS-PAGE. Each fusion protein was confirmed with G57 detection kit. Western blot analysis with the serum of a toxoplasmosis patient revealed antigenicity in proteins expressed by T37. S28, and Al9 but not those by Pl8. X9, Y10, and Z9. Antigenicity of p30 seems to be located either in N-terminal 115 part in the presence of middle 1/3 part or in the oligopeptides between margins of the first and second 1/3 parts.