• The Korean Journal of Mycology
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• v.47 no.1
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• pp.51-61
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• 2019

The goal of this study was to elucidate wild yeast diversity of Geumgang midstream near Sejong metropolitan autonomous city, Korea. Thirty-seven strains of 32 species of wild yeasts were isolated from 43 water and soil samples under the Bulti bridge of Sejong city, Korea. Seven yeasts of each Candida spp. and Cryptococcus spp. were the predominant species isolated from samples near the Bulti bridge. Holtermanniella takashimae SW048 (NNIBRFG9314), Cystofilobasidium infirmominiatum SW013 (NNIBRFG9310), Mrakia cryoconite SW015 (NNIBRFG9316), Pichia sporocuriosa SW085 (NNIBRFG9326) and Cryptococcus aspenensis SW008 (NNIBRFG9309) represented novel yeast strains found in Korea for the first time. All of these previously unrecorded yeasts, except for Mrakia cryoconite SW015 had ascospores and grew well in yeast extract-peptone-dextrose (YPD), yeast extract-malt extract (YM) and potato-extrose (PD) media. Pichia sporocuriosa SW085 grew well in vitamin-free medium and Holtermanniella takashimae SW048, which was a halotolerant wild yeast, grew well YPD medium containing 5 % NaCl. Twenty-six strains representing eight species of wild yeast were isolated from 22 water and soil samples under the Haetmuri bridge of Sejong city, Korea. Candida pseudolambica (12 strains) and Aureobasidium pullulans (11 strains) were the predominant isolates from samples near the Haetmuri bridge. Occultifur kilbournensis HB060 (NNIBRFG9317), Sampaiozyma vanillica HB014 (NNIBRFG9332), Xenoramularia neerlandica HB039 (NNIBRFG9335), Candida norvegica HB315 (NNIBRFG9306), C. melibiosica HB316 (NNIBRFG9305), C. quercuum GB014 (NNIBRFG9307), and C. succiphila GB015 (NNIBRFG9308) represented novel yeast strains recorded in Korea for the first time. O. kilbournensis HB060 and X. neerlandica HB039 did not form ascospores or pseudo-mycelia. All of these previously unrecorded yeasts, except S. vanillica HB014 and X. neerlandica HB039, grew well in vitaminfree medium, and C. norvegica HB315 and C. succiphila GB015, which were halotolerant wild yeasts, which grew well in YPD medium containing 5 % NaCl.

• Journal of Korean Society of Forest Science
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• v.108 no.1
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• pp.40-49
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• 2019

Coarse woody debris (CWD), which is a component of the forest ecosystem, plays a major role in forest energy flow and nutrient cycling. In particular, CWD isolates carbon for a long time and is important in terms of slowing the rate of carbon released from the forest to the atmosphere. Therefore, this study measured the physiochemical characteristics and respiration rate ($R_{CWD}$) of CWD for Larix kaempferi and Pinus rigida in temperate forests in central Korea. In summer 2018, CWD samples from decay class (DC) I to IV were collected in the 14 forest stands. $R_{CWD}$ and physiochemical characteristics were measured using a closed chamber with a portable carbon dioxide sensor in the laboratory. In both species, as CWD decomposition progressed, the density ($D_{CWD}$) of the CWD decreased while the water content ($WC_{CWD}$) increased. Furthermore, the carbon concentrations did not significantly differ by DC, whereas the nitrogen concentration significantly increased and the C/N ratio decreased. The respiration rate of L. kaempferi CWD increased significantly up to DC IV, but for P. rigida it increased to DC II and then unchanged for DC II-IV. Accordingly, except for carbon concentration, all the measured characteristics showed a significant correlation with $R_{CWD}$. Multiple linear regression showed that $WC_{CWD}$ was the most influential factor on $R_{CWD}$. $WC_{CWD}$ affects $R_{CWD}$ by increasing microbial activity and is closely related to complex environmental factors such as temperature and light conditions. Therefore, it is necessary to study their correlation and estimate the time-series pattern of CWD moisture.

• Journal of the Korean Society of International Agriculture
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• v.30 no.4
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• pp.305-312
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• 2018

Clubroot, caused by Plasmodiophora brassicae, is one of the most crucial disease in Kimchi cabbage. Screening disease resistant genetic resources is necessary to develop disease resistant cultivars and conduct related research. We have evaluated the development of clubroot to the 120 genetic resources of Kimchi cabbage introduced from World Vegetable Center and five Asian countries using isolate of Plasmodiophora brassicae collected in Haenam fields in Jeollanam-do Province, Rep. of Korea. This isolate was determined race 2 using differential varieties reported by Kim et al., 2016. IT100384 and IT305623 showed strong resistance, lower than disease index (DI) 1.0. IT100385, 100439, and 135407 showed moderate resistance (1.0

• Korean Journal of Clinical Laboratory Science
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• v.53 no.3
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• pp.225-232
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• 2021

This study sought to investigate the distribution, antimicrobial resistance rate, and bacterial co-infection frequency of non-tuberculous mycobacteria (NTM) in a single center in Incheon, South Korea. A total of 8,258 specimens submitted for tuberculosis (TB)/NTM real-time PCR tests during the years 2015 to 2020 were retrospectively reviewed. In total, 296 specimens (3.6%) were NTM positive, and the positivity increased from 2.5% (30/1,209) in 2015 to 3.8% (66/1,740) in 2020. Of 296 NTM specimens, 54.7% (162/296) were identified as the Mycobacterium avium complex (MAC) followed by the Mycobacterium abscessus complex (MABC) 20.9% (62/296), M. fortuitum 6.4% (19/296) and M. flavescens 3.4% (10/296). Of the NTM-positive specimens, 76.7% (227/296) were tested for drug resistance. The results showed multidrug-resistant NTM in 40.1% (91/227) and extensively drug-resistant NTM in 59.9% (136/227) of these specimens. Of the 145 isolates taken for bacterial culture, bacteria/fungi co-infection with NTM accounted for 43.4% (63/145), in which the most common bacterial species was Klebsiella pneumonia (23.8%, 15/63). This study is the first report on the distribution and antimicrobial resistance of NTM in Incheon. As the proportion of NTM infections increases, active treatment and thorough infection control are required for effective management.

• Korean Journal of Clinical Laboratory Science
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• v.54 no.2
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• pp.110-118
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• 2022

Candidemia is a major cause of nosocomial infections resulting in increased morbidity and mortality. It remains a serious risk in inpatients and increases medical treatment costs. From 2009 to 2018, Candida strains (3,533) isolated from blood culture tests at the S Hospital were analyzed according to the period, year, sex, age, ward, etc. During the entire period, 54,739 of 717,996 blood culture tests showed a positive rate (7.6%) and the Candida isolation rate was 3,533 (6.4%) out of 1,036 patients. Among the Candida isolates, C. albicans was most common (33.8%), followed by C. tropicalis (28.6%), C. glabrata (19.8%), C. parapsilosis (7.8%), and C. krusei (4.0%). In early (2009~2013)/late (2014~2018) isolation, C. tropicalis decreased by 3.8% and C. glabrata increased by 3.4%. After 50 years of age, the higher the separation frequency. C. parapsilosis (31.3%) in 1~10s, C. tropicalis (30.3%) and C. glabrata (27.6%) in 41~50s, and C. tropicalis (28.6%) in 80s are relatively frequent. has been separated C. krusei was isolated in a relatively high proportion from females (60.9%). Therefore, a systematic and continuous nosocomial infection control system should be established for appropriate treatment as per antifungal treatment guidelines. The system should continuously monitor the distribution of Candida species and provide rapid identification results.

• Korean Journal of Ecology and Environment
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• v.56 no.1
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• pp.94-103
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• 2023

Cyanobacterial resting cells, such as akinetes, are important seed cells for cyanobacteria's early development and bloom. Due to their importance, various methods have been attempted to isolate resting cells present in the sediment. Ludox is a solution mainly used for cell separation in marine sediments, but finding an accurate method for use in freshwater is difficult. This study compared the two most commonly used Ludox methods (direct sediment treatment and sediment distilled water suspension treatment). Furthermore, we proposed a highly efficient method for isolating cyanobacterial resting cells and eDNA amplification from freshwater sediments. Most of the resting cells found in the sediment were akinete to the Nostocale and were similar to those of Dolichospermum, Cylindrospermum, and Aphanizomenon. Twenty times more akinetes were found in the conical tube column using the sediment that had no treatment than in the sample treated by suspending the sediment in distilled water. Akinete separated through Ludox were mainly spread over the upper and lower layers in the column rather than concentrated at a specific depth in the column layer. The mibC, Geo, and 16S rDNA genes were successfully amplified using the sediment directly in the sample. However, the amplification products of all genes were not found in the sample in which the sediment was suspended in distilled water. Therefore, 5 g to 10 g of sediment is used without pretreatment when isolating cyanobacterial resting cells from freshwater sediment. Cell isolation and gene amplification efficiency are high when four times the volume of Ludox is added. The Ludox treatment method presented in this study isolates cyanobacterial resting cells in freshwater sediment, and the same efficiency may not appear in other biotas. Therefore, to apply Ludox to the separation of other biotas, it is necessary to conduct a pre-experiment to determine the sediment pretreatment method and the water layer where the target organism exists.

• Tuberculosis and Respiratory Diseases
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• v.57 no.4
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• pp.311-319
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• 2004

Background : It has been well known that bronchiectasis (BE) is a predisposing condition for pulmonary NTM infection, whereas there are some suggestions that BE, especially nodular BE, may be a result of NTM pulmonary infection. This retrospective study was done to investigate the prevalence of NTM pulmonary infection in the patients with BE. Methods : Eight hundred sixty-six patients, who underwent chest CT and sputum AFB examination and had BE detected by chest CT at Asan Medical Center in 2002, were included in this study. They were divided into Group I (bilateral BE, especially in RML, lingular or both lower lobes; 134), Group II (BE accompanied with fibrocavitary lesions commonly found in tuberculosis, usually both upper lobes; 233) and Group III (except Group I, II; 499) according to the radiological findings. Group I was subdivided into Group I+ (62) or Group I- (72) according to the presence or absence of centrilobular nodules, respectively. The sputum AFB examination, clinical and radiological findings were analyzed and compared between groups. Results : The number of patients who had at least one positive NTM culture was significantly higher in Group I+ compared with others (p<0.05); 24.2% in Group I+, 6.9% in Group I-, 9.9% in Group II, 6.0% in Group III and 4.1% in control. The number of patients who had true NTM infection defined by ATS guideline was higher in Group I+ (5, 8.1%) compared with others (p<0.05). In all groups, M. avium-intracellulare comlex was the most common isolates. Conclusion : Even though true NTM pulmonary disease was more prevalent in the patients with nodular BE, especially located in RML, left linguar, or both lower lobes, only a small population of the patients with nodular BE met the ATS diagnostic criteria for NTM pulmonary disease. The other patients in nodular BE group may have subclinical stage of NTM infection or completely different diseases from NTM infection. Long-term clinical studies are needed to clarify this issue.

• Pediatric Infection and Vaccine
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• v.6 no.2
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• pp.210-218
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• 1999

Purpose : As several epidemics of aseptic meningitis had been reported in Korea since 1990, the need of epidemiologic study about enteroviral infections was recognized. We studied epidemiologic and clinical features of enteroviral infections in children. Methods : We analyzed the seasonal occurrence of enteroviral infections and age, sex and clinical diagnosis of the children admitted to five branch hospitals of Hallym University and diagnosed to have enteroviral infections by culture from January 1996 to December 1998. Results : Enterovirus was isolated in 126 out of 245(51.4%) stools, 15 out of 89(16.8%) nasopharyngeal aspirates and 195 out of 1,835(10.6%) cerebrospinal fluids. There were 273 echoviruses(Echo)(197 Echo 30, 46 Echo 9, 17 Echo 6, 13 unclassified), 24 coxsackieviruses B(CB)(11 CB 2, 2 CB 5, 11 unclassified), 7 coxsackieviruses A 24 and 32 unclassified enteroviruses. Yearly number of isolates was 65(46 Echo 9) in 1996, 239(197 Echo 30) in 1997 and 32(15 CB: 9 CB 2) in 1998. Epidemics of enteroviruses occurred mainly during the months May to October. The mean age of the infected children was $62.1{\pm}38.0$ months and 74.6% of the patients were younger than 7 years of age. There were 203 boys and 100 girls and 79.3% of the patients were diagnosed as aseptic meningitis. Conclusions : We confirmed that enteroviral infections occurred in epidemics from late spring to fall during the study period. Enteroviral infections occurred predominantly in boys and the preschool children. Aseptic meningitis was the main illness in the hospitalized children.

• Journal of Life Science
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• v.28 no.2
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• pp.223-228
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• 2018

Lactic acid bacteria were isolated from a variety of fermented seafoods and sea creatures from the East Sea Rim, Korea and were screened for ${\gamma}-amino$ butyric acid-producing (GABA) activity. Through a 16S rRNA sequence analysis, the bacteria of interest, which were GABA-positive on the thin-layer chromatography analysis, were recognized as three isolates of Lactobacillus (Lb.) brevis and one isolate of Lactococcus (Lc.) lactis. Lb. brevis FSFL0004 and FSFL0005 were isolated from fermented anglerfish and Lb. brevis FSFL0036 was derived from salted cutlass fish. The Lc. lactis strain FGL0007 was isolated from the gut of a brown sole flounder. According to HPLC analysis, the GABA contents produced by FSFL0004, FSFL0005, FSFL0036 and FGL0007 were equivalent to $10,754.37{\mu}g/ml$, $13,082.79{\mu}g/ml$, $12,290.19{\mu}g/ml$, and $45.07{\mu}g/ml$ respectively in 1% monosodium glutamate-supplemented methionyl-tRNA synthetase (MRS) broth. The four strains were inoculated in skim milk with 1% monosodium glutamate to commercialize the strains as starter cultures for GABA-enriched dairy products, and TLC results displayed the production of ${\gamma}-amino$ butyric acid by all four strains in the adaptation media. Lc. lactis FGL0007 demonstrated the greatest GABA production ($431.42{\mu}g/ml$) by HPLC analysis. The GABA production by lactic acid bacteria strains in the skim milk demonstrated in the present study may be helpful for the production of GABA-enriched dairy products.

• Journal of Dairy Science and Biotechnology
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• v.33 no.3
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• pp.179-196
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• 2015

Because of our aging population, there is increasing concern about the impact of dementia and age-related cognitive decline. Intense research efforts on effective dietary interventions for the prevention or amelioration of dementia and age-related cognitive decline have indicated that dairy products affect physiological health and potentially healthy brain function during aging. Milk is a rich source of proteins and peptides with nutritional and immunotropic activities. The preparation of biologically active proteins and peptides generally requires enzymatic degradation, chemical modification, or the addition of specific co-factors. Milk-derived preparations are widely available in the food industry in the form of hygiene products and infant formulas. However, milk-derived products could also be applied as preventive or therapeutic measures for a wide-range of pathological conditions not only in neonates and infants but also in adults, including the elderly. Because they have no adverse side effects, milk-derived proteins and peptides could be used as a supplementary treatment for dementia and age-related cognitive decline.