• Mycobiology
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• v.45 no.3
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• pp.129-138
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• 2017

In this study, we aimed to characterize fungal samples from necrotic lesions on collar regions observed in different sweetpotato growing regions during 2015 and 2016 in Korea. Sclerotia appeared on the root zone soil surface, and white dense mycelia were observed. At the later stages of infection, mother roots quickly rotted, and large areas of the plants were destroyed. The disease occurrence was monitored at 45 and 84 farms, and 11.8% and 6.8% of the land areas were found to be infected in 2015 and 2016, respectively. Fungi were isolated from disease samples, and 36 strains were preserved. Based on the cultural and morphological characteristics of colonies, the isolates resembled the reference strain of Sclerotium rolfsii. Representative strains were identified as S. rolfsii (teleomorph: Athelia rolfsii) based on phylogenetic analysis of the internal transcribed spacer and large subunit genes along with morphological observations. To test the pathogenicity, sweetpotato storage roots were inoculated with different S. rolfsii strains. 'Yulmi' variety displayed the highest disease incidence, whereas 'Pungwonmi' resulted in the least. These findings suggested that morphological characteristics and molecular phylogenetic analysis were useful for identification of S. rolfsii.

• The Korean Journal of Mycology
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• v.42 no.4
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• pp.322-327
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• 2014

Subculture is the most common method for preservation fungi, but has a disadvantage of accumulation of spontaneous mutations during the repeated subculture. To reduce the subculture frequency, the effect of preservation period at $4^{\circ}C$ in a slant culture was examined on the mycelia growth and lignocellulolytic enzyme activities of various basidiomycetes. Mushrooms, including Stereum ostrea, Coprinellus micaeus, Trametes versicolor, Hypholoma fasciculare, Wolfiporia extensa, Pleurotus pulmonarius, Piptoporus betulinus and Ganoderma applanatum were not affected by the preservation period more than two years, indicating that they can be maintained by subculture every two years. Some other tested fungal strains showed a significant decrease in both viability and enzyme activity when they were maintained for two years, suggesting that they should be subcultured at least once in a year. A little correlation was found between the recovery of mycelial growth and extracellular enzyme activity. In conclusion, mycelial activity and enzyme activity according to storage period is expected to be a way of deciding on subculture times for fungal preservation.

• Journal of agriculture & life science
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• v.43 no.5
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• pp.57-62
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• 2009

This study was conducted to analyze to the applicability of refined saps of Acer mono, A. mono for. rubripes, A. okamotoanum through sap refining system. 1 species of Bacillus genus, 3-4 species of yeast and 2 species of fungi were detected in the origin sap of three Acer spp. The pH in the origin sap were 6.5, and decreased in refining sap as 6.3-6.4. Sucrose in sugar components was detected in the origin and refining sap of Acer spp., but glucose and fructose were not detected. Compared the origin and refining sap, mineral components decreased slightly in refining sap. These results indicate that refining sap of Acer spp. are drinkable with long-term storage.

• Toxicological Research
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• v.35 no.1
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• pp.1-7
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• 2019

Mycotoxin contamination is a global phenomenon and causes a wide array of negative effects and other complications. This study focused on commonly found mycotoxins in Africa and the possible means of prevention or reduction of their contaminating effects. Mycotoxins are secondary metabolites of mold and fungi; they are generally toxic to living organisms. Hundreds of mycotoxins have been identified thus far, with some, such as aflatoxins, ochratoxins, trichothecenes, zearalenone, fumonisins, and patulin, considered agro-economically important. Several factors contribute to the presence of mycotoxins in food, such as climatic conditions, pest infestation, and poor harvest and storage practices. Exposure to mycotoxins, which occurs mostly by ingestion, leads to various diseases, such as mycotoxicoses and mycoses that may eventually result in death. In light of this, this review of relevant literature focuses on mycotoxin contamination, as well as various methods for the prevention and control of their prevalence, to avert its debilitating consequences on human health. Clear evidence of mycotoxin contamination is present in Africa, and it was therefore recommended that adequate prevention and control of these toxic substances in our food system should be encouraged and that appropriate measures must be taken to ensure food safety as well as the enhanced or long-lifespan of the African populace. Governments, research institutions, and non-governmental organizations should tailor the limited resources available to tackle mycotoxin prevalence, as these will offer the best prospects for successful development of a sustainable food system in Africa.

• The Plant Pathology Journal
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• v.39 no.3
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• pp.265-274
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• 2023

Citrus black rot is a serious disease of citrus plants caused by Alternaria citri. The current study aimed to synthesize zinc oxide nanoparticles (ZnO-NPs) by chemically or green method and investigate their antifungal activity against A. citri. The sizes of synthesized as measured by transmission electron microscope of ZnO-NPs were 88 and 65 nm for chemical and green methods, respectively. The studied prepared ZnO-NPs were applied, in vitro and in situ, at different concentrations (500, 1,000, and 2,000 ㎍/ml) in post-harvest treatment on navel orange fruits to verify the possible control effect against A. citri. Results of in vitro assay demonstrated that, at concentration 2,000 ㎍/ml, the green ZnO-NPs was able to inhibit about 61% of the fungal growth followed by 52% of chemical ZnO-NPs. In addition, scanning electron microscopy of A. citri treated in vitro with green ZnO-NPs showed swelling and deformation of conidia. Results showed also that, using a chemically and green ZnO-NPs at 2,000 ㎍/ml in situ in post-harvest treatment of orange, artificially-infected with A. citri, has reduced the disease severity to 6.92% and 9.23%, respectively, compared to 23.84% of positive control (non-treated fruits) after 20 days of storage. The out findings of this study may contribute to the development of a natural, effective, and eco-friendly strategy for eradicating harmful phytopathogenic fungi.

• Mass Spectrometry Letters
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• v.15 no.1
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• pp.40-48
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• 2024

Capacity of the analytical/quantitative evaluation techniques to satisfy both qualitative and quantitative considerations for effective extraction of marigold oleoresins/xanthophylls and their potential as anti-mycotic and antioxidant activity was assessed. Accelerated solvent extraction (ASE), Soxhlet extraction (SE), Supercritical fluid extraction (SCFE), Cold extraction (CE), and ultrasonically assisted extraction (USE) techniques were evaluated for extraction of oleoresin/xanthophyll content from Tagetes erecta (Var. Pusa Narangi Genda) with respect to solvent consumption, extraction time, reproducibility, and yield. Followed by the antifungal and antioxidant activity evaluation. The overall yield of Tagetes oleoresin was higher in ASE (64.5 g/kg) followed by SE (57.3 g/kg), USE (50.7 g/kg), SCFE (45.3 g/kg) and CE (31.6 g/kg). The lutein esters represented more than 80% of the constituents. Further, xanthophyll/ lutein content in oleoresin was found to be quite higher in HPLC (r2 = 0.996) analysis than in the AOAC recommended UV spectrophotometer analysis. The oleoresin exhibited moderate antioxidant activity (DPPH assay) and antifungal activity against three phytopathogenic fungi. Based on the various parameters, the reproducibility of ASE was better (0.3-8.0%) than that of SE (0.5-12.9%), SCFE (0.2-9.4%), USE (0.3-12.4%) and CE (0.8-15.3%). ASE with (RSD 1.6%) is preferred being faster, reproducible, uses less solvent, robust and automation allows sequential extraction of the sample in less time.

• Korean Journal of Food Science and Technology
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• v.24 no.4
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• pp.376-381
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• 1992

In order to study the effect of modified atmosphere storage on extending shelf life of mushrooms, oyster mushroom and Shiitake were wrapped with polyethylene film (PE, $50\;{\mu}m$), and stored at $0.5^{\circ}C$. Mushrooms packed with conventional hardboard box (4kg) lost marketability within $5{\sim}6$ days due to weight loss, shrinkage, browning, spore formation and/or mycellium growth. PE-packing could prevent or retard the deterioration of the mushrooms in the aspects of appearance, texture, discoloration, and microbial contamination. This situation can be best characterized by the reduced respiration rate resulted from the elevated level of carbon dioxide and the reduced level of oxygen in the bag. Although the appearance of the oyster mushroom was maintained for one month, its shelf life was limited to 15 days because of tissue softening. Discoloration of the pileus of shiitake mushroom appears to be the most important factor to determine its marketability. For example, extension of shelf life of Dongo was limited to 15 days, principally due to the browning of the pileus. Shelf life of Hawgo whose color of the pileus changed little over the experimental period, however, could be extened to more than one month.

• The Korean Journal of Mycology
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• v.32 no.1
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• pp.39-44
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• 2004

Gastrodia elata has been cultivated using mycorrizal fungi including Armillaria mellea as an energy source (myco-hetrotrophy) because it is aphyllous and achlorophyllous archid. But the yields of G. elata have been recently decreased owing to the degeneration of spawn tuber arised from successive asexual reproduction. Therefore, this study was carried out to solve this degeneration by seed germination, namely sexual reproduction. The seed germination of G. elata was excellent on the fallen leaves medium of oak tree. The fruetification rate of the capsule of G. elata by artificial pollination was 94.1% and better than natural pollination. The living weight of capsules of G. elata suitable for seeds germination was above 31 mg. The middle-matured seeds and matured seeds of capules were largely germinated, while the immatured seeds was small germinated. The storage temperature of the cropped capsules suitable for a favorable seed germination was $0{\sim}5^{\circ}C$ and the storage period of it was one month.

• The Plant Pathology Journal
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• v.17 no.3
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• pp.141-148
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• 2001

Postharvest decay of onion bulbs was examined by inspecting the commercial packages in the market or in storage. Bulb rot incidence was unexpectedly high, and onion bulbs with 1st quality grade were rotten most severely by 51%, followed by 32% for 2nd and 21% for 3rd grades. This indicates that larger bulbs had higher incidences of bulb rots. Major pathogens associated with basal and neck rots were Fusarium oxysporum and Aspergillus sp. or Botrytis allii, respectively, of which basal rot was most prevalent and damaging during storage. Among the epiphytic microorgani는 from onion plants, several Bacillus and Paenibacillus spp. and previously selected Pseudomonas putida and Trichoderma harzianum had inhibitory efficacy against bulb rot pathogens. Among these B. amyloliquefaciens BL-3, Paenibacillus polymyxa BL-4, and P. putida Cha 94 were highly inhibitory to conidial germination of F. oxysporum and B. allii. P. putida Cha 94, B. amyloliquefaciens BL-3, P. polymyxa BL-4, and T. harzianum TM were applied in the rhizoplane of onion at transplanting. Initially antagonist populations decreased rapidly during the first one month. However, among these antagonists, rhizoplane population densities of BL-3, Cha 94, and TM were consistently high thereafter, maintaining about 10$^4$-10$^{5}$ cells or spores per gram of onion root up to harvest time. The other bacterial antagonist BL-4 survived only for two months. TM was the most effective biocontrol agent against basal rot, with the number of rotten bulbs recorded at 4%, while that of the control was 16%. Cha 94 was effective for the first 20 days, but basal rot increased thereafter and had about the same control efficacy as that of BL-3 and BL-4. When the antagonists were applied to the topping areas of onion bulbs at harvest, TM was the most effective in protecting the stored onion bulbs from neck rotting. The second effective antagonist was BL-3. TM and BL-3 completely suppressed the neck rot in another test, suggesting that biocontrol of postharvest decay of onion using these microorganisms either at the time of transplanting or at harvesting may be promising.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.9
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• pp.1225-1229
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• 2007

Cold buckwheat noodles with 3% vitamin D2 enriched Siitake mushroom and seaweed derived calcium (Aquacal) added as functional ingredients were developed. For the prediction of shelf-life of these cold buckwheat noodles, classified as unsterilized cooked noodles, bacterial counts and sensory evaluations were examined during 8 days under refrigerated conditions (5oC) and 8 weeks of storage under frozen conditions $(-18^{\circ}C)$. Results of bacterial count showed that cold buckwheat noodles were microbiologically safe within 6 days at the storage temperature of $5^{\circ}C$ and the shelf-life of these noodles could be extended to 8 whole weeks when stored at $-18^{\circ}C$. Apparent qualities (off-flavor and fungi development) of cold buckwheat noodles kept in $5^{\circ}C$ were not decreased within 8 days. Sensory characteristics (gloss, mushroom flavor, bitterness, chewiness and elasticity) of noodles were not changed during 8 weeks at $-18^{\circ}C$.