• Research in Plant Disease
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• v.28 no.3
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• pp.172-178
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• 2022

The graft cactus (Gymnocalycium mihanovichii) continues to be exported to more than 20 countries worldwide. In April 2021, typical bacterial symptoms of soft rot were observed in the graft cactus (cv. Yeonbit) in Goyang, Gyeonggi-do, Korea, resulting in economic losses in cactus production. The stems turned dark brown and the flowers were covered with black rot. The bacterial strain designated as KNUB-01-21 was isolated from infected stems and flowers. The results of the morphological and biochemical tests of the isolate were similar to those of Pectobacterium brasiliense. For molecular analysis, the 16S rRNA region and three housekeeping genes (dnaX, leuS, and recA) of the strain KNUB-01-21 were amplified. Based on the results of the molecular analysis and morphological and biochemical tests, KNUB-01-21 was identified as P. brasiliense. The pathogenicity of KNUB-01-21 on graft cactus was confirmed by an inoculation test. Artificial inoculation using P. brasiliense KNUB-01-21 produced soft rot symptoms on the grafted cactus, and the same bacterium was re-isolated and re-identified. This is the first report of P. brasiliense causing soft rot in graft cactus in Korea.

• Food Science and Preservation
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• v.30 no.1
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• pp.28-41
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• 2023

Non-aflatoxigenic Aspergillus oryzae and aflatoxigenic A. flavus cannot be clearly identified by partial sequencing of the internal transcribed spacer (ITS) and 18S ribosomal ribonucleic acid (18S rRNA) regions. This study aimed to compare the accuracy among three aflatoxin detection methods using ultra-performance liquid chromatography (UPLC), high-performance liquid chromatography (HPLC), and an enzyme-linked immunosorbent assay (ELISA) kit and to select the non-aflatoxigenic Aspergillus sp. isolated from soybean paste. All analytical methods were suitable according to the international standards of Codex Alimentarius FAO-WHO (CODEX) or the Ministry of Food and Drug Safety (MFDS). UPLC exhibited the best of limit of detection (LOD) and limit of quantification (LOQ). Based on UPLC, HPLC, and the ELISA kit assay, the P5 and P7 strains isolated from soybean paste had 1,663.49, 1,468.12, and >20 ㎍/kg and 1,470.08, 1,056.73, and >20 ㎍/kg, respectively, detected and re-identified as A. flavus. In contrast, the P3 and P4 strains (A. oryzae), which were detected below the MFDS standards in all assays, were confirmed as non-aflatoxigenic fungi. Among the methods evaluated for quantitative analysis of aflatoxin, UPLC and HPLC are superior in terms of accuracy, and the ELISA kit rapidly detects low concentrations of aflatoxin. Furthermore, this study demonstrates that any Aspergillus sp. isolated for use as a fermentation starter should be analyzed for potential aflatoxin production using UPLC and HPLC for accurate quantitative analysis or ELISA for the rapid detection of low-level concentrations of aflatoxin.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.6
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• pp.888-895
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• 2015

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and subsequent sub-cloning and sequencing were used in this study to analyze the molecular phylogenetic diversity and spatial distribution of bacterial communities in different spatial locations during the cooling stage of composted swine manure. Total microbial DNA was extracted, and bacterial near full-length 16S rRNA genes were subsequently amplified, cloned, RFLP-screened, and sequenced. A total of 420 positive clones were classified by RFLP and near-full-length 16S rDNA sequences. Approximately 48 operational taxonomic units (OTUs) were found among 139 positive clones from the superstratum sample; 26 among 149 were from the middle-level sample and 35 among 132 were from the substrate sample. Thermobifida fusca was common in the superstratum layer of the pile. Some Bacillus spp. were remarkable in the middle-level layer, and Clostridium sp. was dominant in the substrate layer. Among 109 OTUs, 99 displayed homology with those in the GenBank database. Ten OTUs were not closely related to any known species. The superstratum sample had the highest microbial diversity, and different and distinct bacterial communities were detected in the three different layers. This study demonstrated the spatial characteristics of the microbial community distribution in the cooling stage of swine manure compost.

• Korean Journal of Environmental Biology
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• v.28 no.4
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• pp.218-222
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• 2010

This study was carried out to investigate the changes in the storage characteristics of the Korean traditional raw rice wine (RRW) treated with Korean sun-dried salts and gamma rays. Nowadays, RRWs have received attention because they are a nutritious food with health-stimulating properties. But the rapid deterioration of the fermented RRW is one of the serious problems for brewing and marketing in the world. Actually, the expiry date of the RRW is around a week and this has been a biggest disadvantage of the RRW. The goal of this study was to make it of high quality and extend the period of circulation of the RRW. A lactic acid bacterium was isolated from the RRW. The 16S rRNA sequences of isolates showed 98% homology with the Lactobacillus fermentum. These results suggested that could be manageable improve the shelf life with addition of the sun-dried salts and irradiation with gamma rays.

• Journal of Microbiology and Biotechnology
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• v.28 no.3
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• pp.454-464
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• 2018

Salivary microbiota alterations can correlate with dental caries development in children, and mechanisms mediating this association need to be studied in further detail. Our study explored salivary microbiota shifts in children and their association with the incidence of dental caries with dentine involvement. Salivary samples were collected from children with caries and their subsequently matched caries-free controls before and after caries development. The microbiota was analyzed by 16S rRNA gene-based high-throughput sequencing. The salivary microbiota was more diverse in caries-free subjects than in those with dental caries with dentine involvement (DC). Although both groups exhibited similar shifts in microbiota composition, an association with caries was found by function prediction. Analysis of potential microbiome functions revealed that Granulicatella, Streptococcus, Bulleidia, and Staphylococcus in the DC group could be associated with the bacterial invasion of epithelial cells, phosphotransferase system, and ${\text\tiny{D}}-alanine$ metabolism, whereas Neisseria, Lautropia, and Leptotrichia in caries-free subjects could be associated with bacterial motility protein genes, linoleic acid metabolism, and flavonoid biosynthesis, suggesting that functional differences in the salivary microbiota may be associated with caries formation. These results expand the current understanding of the functional significance of the salivary microbiome in caries development, and may facilitate the identification of novel biomarkers and treatment targets.

• Journal of Microbiology and Biotechnology
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• v.28 no.9
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• pp.1536-1541
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• 2018

A yellowish, flexirubin-pigment-producing strain $I3-3^T$ was isolated from river water in Iksan, the Republic of Korea. The strain was gram-negative, aerobic, non-motile, showed catalase and oxidase activities, and could grow at a temperature range of $10-35^{\circ}C$, pH 5.0-10 and 0-2.0% (w/v) of NaCl. The major fatty acids were iso-$C_{15:0}$, iso-$C_{17:0}$ 3-OH and summed feature 3 (comprising $C_{16:1}{\omega}7c$ and/or $C_{16:1}{\omega}6c$). The isolate contained phosphatidylethanolamine, one aminolipid, and two unidentified lipids as the major polar lipids. Menaquinone-6 (MK6) was the major respiratory quinone. The G+C content of the genomic DNA of strain $I3-3^T$ was 35.6%. Comparison of the 16S rRNA gene sequence with the sequences of the closely related type strains showed highest sequence similarity of 96.95% and 96.93% to Flavobacterium nitrogenifigens $NXU-44^T$ and Flavobacterium compostarboris $15C3^T$, respectively. Based on phenotypic and phylogenetic distinctiveness, strain $I3-3^T$ is considered as a member of novel species within the genus Flavobacterium, for which Flavobacterium amnigenum sp. nov. is proposed. The type strain is $I3-3^T$ (=KCTC $52884^T$ =NBRC $112871^T$).

• The Korean Journal of Mycology
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• v.46 no.3
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• pp.345-351
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• 2018

A fungal isolate denoted NC14-264 was isolated from the soil in Jeongeup, Jeollabuk-do, Korea. Species in genus Plectosphaerella are pathogenic to several plant species, leading to fruit, root, and collar rot and collapse. In this study, a strain NC14-264 belonging to the Plectosphaerella was isolated from the soil and identified. Colonies were moderately grown, reaching 54 mm in diameter on potato dextrose agar, 49 mm on malt extract agar, and 55 mm on oatmeal agar at $25^{\circ}C$ after 10 days of incubation. Most Plectosphaerella species are distinguishable morphologically by irregular chlamydospores and different proportions of phialides and conidia. Based on morphological features and phylogenetic analysis using the internal transcribed spacer region and partial 28S rRNA gene sequences, the isolated fungus was identified as Plectosphaerella sinensis belonging to the Plectosphaerellaceae. This is the first report of P. sinensis in Korea.

• Tuberculosis and Respiratory Diseases
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• v.76 no.1
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• pp.30-33
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• 2014

We report the first Korean case of lung diseases caused by Mycobacterium abscessus subsp. bolletii in a previously healthy male, except for a previous history of pulmonary tuberculosis and bronchiectasis. All serial isolates are identified as M. abscessus subsp. bolletii by multi-locus sequence analysis based on the hsp65, rpoB, and 16S rRNA fragments. At the genetic level, the isolate has the erm(41) gene with a T28 sequevar, associated with clarithromycin resistance, and no rrl mutation. The isolate is resistant to clarithromycin. Although the symptoms and radiographic findings have improved after combination of antibiotics, the follow-up sputum cultures are persistently positive.

• Microbiology and Biotechnology Letters
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• v.41 no.3
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• pp.278-283
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• 2013

A gram-positive, rod-shaped, spore-forming, motile thermophilic bacterium was isolated from a sterilization oven. The microorganism GWE1, formally named Geobacillus wiegelii identified as a member of the genus Geobacillus. GWE1 grew under aerobic conditions of between $60-80^{\circ}C$ (optimum $670^{\circ}C$), in a pH range of 3.0-8.0 (optimum $pH^{70^{\circ}C}$ 5.8), and between 0 and 2 M NaCl (optimum 0.3 M). The membrane polar lipids were dominated by branched saturated fatty acids, which included as the major constituents; iso-15:0 (13.3%), 16:1(${\omega}7$) (12.8%), 16:0 (28.5%), iso-17:0 (13.5%) and anteiso-17:0 (12.3%). The DNA G+C content was 47.2 mol% (determined by HPLC). The 16S rRNA gene sequence of GWE1 showed a high similarity with Geobacillus caldoxylosilyticus (97%). However, the level of DNA-DNA relatedness was only 58%. These data suggest that GWE1 is probably a novel specie of the genus Geobacillus.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 2004.05a
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• pp.224-228
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• 2004

2002년 8월부터 11월까지 전국 27개 지역에서 희나리 고추를 포함하고 있는 태양초 시료 40군을 수집하여 총 197주의 곰팡이를 분리하였다. 이 곰팡이들을 고체배지상에서의 번식속도, 분생포자의 모양 및 배양특성의 특성에 따라 6개의 group오로 나누었고 각 group에서 대표가 되는 30 균주를 임의로 선택하여 18S rRNA gene 염기서열을 분석하여 동정하였다. 희나리 곰팡이 중 에서 Colletotrichum 속 곰팡이가 66.5% (131/197)를 차지하여 가장 많이 분리되었고, 기타 Diaporthe phaseolorum var. sojae (28주, 14.2%), Alternaria alternata (17주, 8.6%), Botryosphaeria ribis (9주, 4.6%) Aspergillus oryzae var. oryzae (3주 1.5%) 및 Fusarium incarnatum (9주, 4.6%)이 동정되었다. 각 group에서 임의적으로 한 균주씩을 선택하여 현미에 배양한 뒤 쥐(rat)에 투여시험한 결과 A. alternata를 접종한 사료를 먹인 실험동물이 2주내에 모두 죽었으며 다른 곰팡이를 배양한 사료에는 특이한 영향이 없었다. A. alternata 곰팡이를 현미와 고추즙에 배양하여 주요 독소들을 분석한 결과 17주의 곰팡이 중 8주가 현미와 고추즙에서 많은 양 (현미: $488{\sim}1572\;{\mu}g/g$, 고추즙: $115{\sim}1050\;{\mu}g/g$)의 tenuazonic acid (TeA)를 생성하였다. alternariol(AOH)독소와 alternariol monomethyl ether (AME)는 현미에 배양했을 때만 흔적량 내지 소량씩이 관찰되었다. Alternaria 독소 중 altenuene는 현미와 고추즙 배지 모두에서 검출되지 않았다.