Browsing by Author "Lee, Hyang Burm"

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    Alternaria in food: Ecophysiology, mycotoxin production and toxicology
    (Hangug Gynnhaghoi, 2016-06-30) Lee, Hyang Burm; Patriarca, Andrea; Magan, Naresh
    Alternaria species are common saprophytes or pathogens of a wide range of plants pre- and post-harvest. This review considers the relative importance of Alternaria species, their ecology, competitiveness, production of mycotoxins and the prevalence of the predominant mycotoxins in different food products. The available toxicity data on these toxins and the potential future impacts of Alternaria species and their toxicity in food products pre- and post-harvest are discussed. The growth of Alternaria species is influenced by interacting abiotic factors, especially water activity (a w ), temperature and pH. The boundary conditions which allow growth and toxin production have been identified in relation to different matrices including cereal grain, sorghum, cottonseed, tomato, and soya beans. The competitiveness of Alternaria species is related to their water stress tolerance, hydrolytic enzyme production and ability to produce mycotoxins. The relationship between A. tenuissima and other phyllosphere fungi has been examined and the relative competitiveness determined using both an Index of Dominance (I D ) and the Niche Overlap Index (NOI) based on carbon-utilisation patterns. The toxicology of some of the Alternaria mycotoxins have been studied; however, some data are still lacking. The isolation of Alternaria toxins in different food products including processed products is reviewed. The future implications of Alternaria colonization/infection and the role of their mycotoxins in food production chains pre- and post-harvest are discussed.
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    Alternaria in food: Ecophysiology, mycotoxin production and toxicology- Erratum
    (Hangug Gynnhaghoi, 2015-09-01) Lee, Hyang Burm; Patriarca, Andrea; Magan, Naresh
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    Aspergillus ullungdoensis sp. nov., Penicillium jeongsukae sp. nov., and other fungi from Korea
    (Elsevier, 2024-12) Lee, Hyang Burm; Nguyen, Thuong T.T.; Noh, So Jeong; Kim, Dong Hee; Kang, Ki Hyun; Kim, Su Jin; Kirk, Paul M.; Avery, Simon V.; Medina, Angel; Hallsworth, John E.
    Eurotiales fungi are thought to be distributed worldwide but there is a paucity of information about their occurrence on diverse substrates or hosts and at specific localities. Some of the Eurotiales, including Aspergillus and Penicillium species, produce an array of secondary metabolites of use for agricultural, medicinal, and pharmaceutical applications. Here, we carried out a survey of the Eurotiales in Korea, focusing on soil, freshwater, and plants (dried persimmon fruits and seeds of Perilla frutescens, known commonly as shiso). We obtained 11 species that—based on morphology, physiology, and multi-locus (ITS, BenA, CaM, and RPB2) phylogenetic analyses—include two new species, Aspergillus ullungdoensis sp. nov. and Penicillium jeongsukae sp. nov., and nine species that were known, but previously not described in Korea, Aspergillus aculeatinus, Aspergillus aurantiacoflavus, Aspergillus croceiaffinis, Aspergillus pseudoviridinutans, Aspergillus uvarum, Penicillium ferraniaense, Penicillium glaucoroseum, Penicillium sajarovii, and one, Penicillium charlesii, that was isolated from previously unknown host, woodlouse (Porcellio scaber). We believe that biodiversity surveys and identifying new species can contribute to set a baseline for future changes in the context of humanitarian crises such as climate change.
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    The influence of environmental factors on growth and interactions between Embellisia allii and Fusarium oxysporum f. sp. cepae isolated from garlic
    (Elsevier, 2010-04) Lee, Hyang Burm; Magan, Naresh
    Embellisia allii results in the formation of a bulb canker and black soot on the surface of different alliums and it has been frequently detected on garlic bulbs together with the spoilage fungus, Fusarium oxysporum f. sp. cepae, which causes bulb basal plate rot. In this study, the influence of water activity (aw) and temperature on mycelial growth of E. allii and F. oxysporum f. sp. cepae, conidial size and sporulation of E. allii, interactions between E. allii and F. oxysporum f. sp. cepae, Index of Dominance (ID), and in situ virulence on garlic were examined. Mycelial growth of E. allii was optimal (5.97 mm/day) at 0.995 aw and 25 °C, slower at 30 °C. However, almost no growth occurred at 0.937 aw/30 °C. F. oxysporum f. sp. cepae grew faster than E. allii, (6.3–7.4 mm/day) at 30 °C. Interactions between E. allii and F. oxysporum f. sp. cepae were influenced by aw and temperature. Sporulation of E. allii was more abundant on PDA than on MEA, especially at high aw (0.995) and low temperature (20 °C), but almost no sporulation occurred at 30 °C regardless of nutritional medium or aw level. The spore length of E. allii was longer on PDA than MEA, and was significantly influenced by water availability. F. oxysporum f. sp. cepae was competitive against E. allii and had a higher ID value in comparison with E. allii especially at a higher temperature (30 °C). In situ virulence tests showed that E. allii was weakly virulent on the garlic bulb cloves while that of F. oxysporum f. sp. cepae was highly dependent on aw.
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    Mycotoxin production of Alternaria strains isolated from Korean barley grains determined by LC-MS/MS
    (Elsevier, 2018-01-03) Nguyen, Thuong T. T.; Kim, Jueun; Jeon, Sun Jeong; Lee, Chul Won; Magan, Naresh; Lee, Hyang Burm
    Twenty-four Alternaria strains were isolated from barley grain samples. These strains were screened for the production of mycotoxins on rice medium using thin layer chromatography. All 24 strains produced at least one of the five mycotoxins (ALT, AOH, ATX-I, AME, and TeA). Three representative strains, namely EML-BLDF1-4, EML-BLDF1-14, and EML-BLDF1-18, were further analyzed using a new LC–MS/MS-based mycotoxin quantification method. This method was used to detect and quantify Alternaria mycotoxins. We used positive ion electrospray mass spectrometry with multiple reaction mode (MRM) for the simultaneous quantification of various Alternaria mycotoxins produced by these strains. Five Alternaria toxins (ALT, ATX-I, AOH, AME, and TeA) were detected and quantified. Sample preparation included methanol extraction, concentration, and injection into LC–MS/MS. Limit of detection ranged from 0.13 to 4 μg/mL and limit of quantification ranged from 0.25 to 8 μg/mL.