Mycobiota of ground red pepper and their aflatoxigenic potential

Hyeonheui Ham,Sosoo Kim,Min-Hee Kim,Soohyung Lee,Sung Kee Hong,Jae-Gee Ryu,Theresa Lee 한국미생물학회 2016 The journal of microbiology Vol.54 No.12

To investigate contamination of ground red pepper with fungi and mycotoxin, we obtained 30 ground red pepper samples from 15 manufacturers in the main chili-pepper-producing areas in Korea. Fungal contamination was evaluated by spreading diluted samples on potato dextrose agar plates. The total fungi counts ranged from 0 to 7.3 × 103 CFU/g. In the samples, the genus Aspergillus had the highest incidence, while Paecilomyces was isolated most frequently. The next most frequent genera were Rhizopus, Penicillium, Cladosporium, and Alternaria. Within Aspergillus, A. ruber was predominant, followed by A. niger, A. amstelodami, A. ochraceus, A. terreus, A. versicolor, A. flavus, and A. fumigatus. The samples were analyzed for aflatoxins, ochratoxin A, and citrinin by ultraperfomance liquid chromatography (UPLC) with a fluorescence detector. Ochratoxin A was detected from three samples at 1.03‒2.08 μg/kg, whereas no aflatoxins or citrinin were detected. To test the potential of fungal isolates to produce aflatoxin, we performed a PCR assay that screened for the norB-cypA gene for 64 Aspergillus isolates. As a result, a single 800-bp band was amplified from 10 A. flavus isolates, and one Aspergillus sp. isolate. UPLC analyses confirmed aflatoxin production by nine A. flavus isolates and one Aspergillus sp. isolate, which produced total aflatoxins at 146.88‒909.53 μg/kg. This indicates that continuous monitoring of ground red pepper for toxigenic fungi is necessary to minimize mycotoxin contamination.

Discrimination and Detection of Erwinia amylovora and Erwinia pyrifoliae with a Single Primer Set

함현희(Hyeonheui Ham),Kyongnim Kim,양수인(Suin Yang),공현기(Hyun Gi Kong),이미현(Mi-Hyun Lee),Yong Ju Jin,박동석(Dong Suk Park) 한국식물병리학회 2022 Plant Pathology Journal Vol.38 No.3

Erwinia amylovora and Erwinia pyrifoliae cause fire blight and black-shoot blight, respectively, in apples and pears. E. pyrifoliae is less pathogenic and has a narrower host range than that of E. amylovora. Fire blight and black-shoot blight exhibit similar symptoms, making it difficult to distinguish one bacterial disease from the other. Molecular tools that differentiate fire blight from black-shoot blight could guide in the implementation of appropriate management strategies to control both diseases. In this study, a primer set was developed to detect and distinguish E. amylovora from E. pyrifoliae by conventional polymerase chain reaction (PCR). The primers produced amplicons of different sizes that were specific to each bacterial species. PCR products from E. amylovora and E. pyrifoliae cells at concentrations of 104 cfu/ml and 107 cfu/ml, respectively, were amplified, which demonstrated sufficient primer detection sensitivity. This primer set provides a simple molecular tool to distinguish between two types of bacterial diseases with similar symptoms.

2015‒2019년 국내 과수 화상병 발생

함현희(Hyeonheui Ham),이영기(Young-Kee Lee),공현기(Hyun Gi Kong),홍성준(Seong Jun Hong),이경재(Kyong Jae Lee),오가람(Ga-Ram Oh),이미현(Mi-Hyun Lee),이용환(Yong Hwan Lee) 한국식물병리학회 2020 식물병연구 Vol.26 No.4

과수 화상병을 일으키는 Erwinia amylovora는 국내에서 금지병원균으로 지정되어 화상병 발생 시, 중앙 정부의 진단을 근거로 기주를 매몰하는 공적 방제가 실시되고 있다. 국내 과수 화상병은 2015년 안성, 천안 및 제천의 43농가에서 발생하여 42.9 ha를 매몰한 것을 시작으로, 2019년 발생 지역이 11개 시군으로확산되었으며, 총 348농가 260.4 ha가 매몰되었다. 배나무 화상병은 주로 경기남부와 충남에서 발생되었고, 발생 건수가 연평균 29±9.2건으로 매년 비교적 고르게 발생되었으며 20-30년생 과수에서 발병 비율이 가장 높았다. 반면, 사과나무 화상병은 주로 경기북부, 강원, 충북에서 발생되었고, 발생 건수가 연평균 41±57.6건으로 2018‒2019년 발생건수가 크게 증가하였으며, 20년 이하의 과수의 발병 비율이 높았다. 국내 과수 화상병은 어린 사과나무에서 병의 확산이 빠르므로, 특히 미성숙과수가 식재된 과원에서는 화상병이 발병하지 않도록 약제를적기에 살포하는 등 예방을 철저히 하고, 발병 시 신속히 방제해야 한다. Erwinia amylovora, a causal bacterium of fire blight disease, is registered as a prohibited quarantine pathogen in Korea. To control the disease, the government should diagnose the disease, dig and bury the host trees when fire blight occurs. Fire blight was the first reported in 43 orchards of Anseong, Cheonan, and Jecheon in 2015, and 42.9 ha of host trees were eradicated. However, the disease spread to eleven cities, so that 348 orchards and 260.4 ha of host trees were eradicated until 2019. Fire blight of Asian pear occurred mainly in the southern part of Gyeonggi, and Chungnam province, on average of 29±9.2 orchards per year. And the age of the infected trees were mostly 20–30 years old. In apple trees, the disease occurred mainly in the northern part of Gyeonggi, Gangwon, and Chungbuk province, on average of 41±57.6 orchards per year, increased highly in 2018 and 2019. The age of infected apple trees were under 20 years old. Therefore, because the disease spread rapidly in young apple trees, spraying control agents to the trees in a timely manner and removing infected trees quickly are important to prevent the spread of fire blight in the orchard of immature trees.

2019년 국내 사과와 배 화상병 대발생과 그 특징

함현희(Hyeonheui Ham),이경재(Kyong Jae Lee),홍성준(Seong Jun Hong),공현기(Hyun Gi Kong),이미현(Mi-Hyun Lee),김현란(Hyun-Ran Kim),이용환(Yong Hwan Lee) 한국식물병리학회 2020 식물병연구 Vol.26 No.4

2019년 국내의 사과와 배에 화상병이 크게 발생한 원인을 파악하기 위하여 화상병 발생한 30개 과원을 대상으로 각각의 발생 상황과 농가 면담을 통해 경종적 특징 등을 조사하였다. 화상병은 이미 감염된 지 2년 이상 오래 된 과원에서 대부분 발생하였는데, 이런 원인은 (1) 농가가 병 증상을 정확히 알지 못하여 농작업과 방화곤충 등을 통해 과원 내에서 퍼지게 되고, (2) 방화곤충이나 농작업자 등에 의해 처음 발생 과원에서 주변과수원으로 확산되었고, (3) 동일 경작자 또는 공동 농작업자에 의해 근거리 또는 원거리로 확산된 것이라고 추정할 수 있다. (4) 이런 일련의 과정이 새롭게 확산된 지역에서 반복되다가 농가들이 화상병을 알게 되면서 신고가 증가한 것이 2019년 화상병 대발생의 일련의 원인이라고 추정할 수 있었다. 국내에서 화상병 확산을 최소화하기 위해서는 조기진단을 위한 철저한 농업인 교육과 무병징 식물체에서도 화상병균 진단이 가능한 정량적 검출기술이 요구되고 있다. 또한 큰 열매를 주로 생산하는국내 재배법에 적합한 약제방제 체계 개발이 필요하다. 화상병방제에서 가장 중요한 가지의 궤양 증상, 묘목, 양봉장 등의 전염원 관리를 위해서 과원별 병원균의 분자역학연구를 통해 정확한 확산경로를 구명할 것을 제안한다. To find out the cause of the fire blight outbreak in apples and pears of Korea in 2019, we investigated disease appearing situation of thirty fire blight infected orchards, and interviewed farmers to determine the cultivation characteristics. Fire blight occurred mostly in orchards that had infected more than 2 years before. The cause of this were as follows: farmers did not know the symptoms of the disease properly. It is presumed that it has spread from the first occurrence to the surrounding orchards by flower-visiting insects or farmers and to a short distance or a long distance by the same cultivator or co-farmer. These series of processes repeated in the newly spreading area, and then disease reports increased as farmers became aware of fire blight. To minimize the spread of fire blight in Korea, it suggested that thorough education of farmers for early diagnosis and quantitative detection technology that can diagnose even in no symptom showing plants. And chemical or biological spraying systems suitable for domestic cultivation methods, which are producing large fruits, and molecular epidemiological studies of pathogens.

Erratum : Microbial Community Dysbiosis and Functional Gene Content Changes in Apple Flowers due to Fire Blight

Kong, Hyun Gi,Ham, Hyeonheui,Lee, Mi-Hyun,Park, Dong Suk,Lee, Yong Hwan The Korean Society of Plant Pathology 2021 Plant Pathology Journal Vol.37 No.5

Microbial Community Dysbiosis and Functional Gene Content Changes in Apple Flowers due to Fire Blight

Hyun Gi Kong,Hyeonheui Ham,Mi-Hyun Lee,Dong Suk Park,Yong Hwan Lee 한국식물병리학회 2021 Plant Pathology Journal Vol.37 No.4

Despite the plant microbiota plays an important role in plant health, little is known about the potential interactions of the flower microbiota with pathogens. In this study, we investigated the microbial community of apple blossoms when infected with Erwinia amylovora. The long-read sequencing technology, which significantly increased the genome sequence resolution, thus enabling the characterization of fire blight- induced changes in the flower microbial community. Each sample showed a unique microbial community at the species level. Pantoea agglomerans and P. allii were the most predominant bacteria in healthy flowers, whereas E. amylovora comprised more than 90% of the microbial population in diseased flowers. Furthermore, gene function analysis revealed that glucose and xylose metabolism were enriched in diseased flowers. Overall, our results showed that the microbiome of apple blossoms is rich in specific bacteria, and the nutritional composition of flowers is important for the incidence and spread of bacterial disease.

저장 중 겉보리에 발생하는 곰팡이와 곰팡이독소 변화

함현희,백지선,이미정,이데레사,홍성기,이승돈,Ham, Hyeonheui,Baek, Jiseon,Lee, Mijeong,Lee, Theresa,Hong, Sung-Kee,Lee, Seungdon 한국식품저장유통학회 2017 한국식품저장유통학회지 Vol.24 No.6

본 연구는 곰팡이독소에 안전한 보리 저장법을 수립하기 위해 다양한 저장환경 중 겉보리에 발생하는 곰팡이와 곰팡이독소를 측정하였다. 두 지역에서 수집한 겉보리를 상온 창고 2곳, 저온창고, $15^{\circ}C/65%$ 항온항습실 및 종자저장고에 6개월간 저장하면서 장소별 온도, 상대습도 및 곡물수분함량을 측정하였으며 0, 1, 3 및 6개월 후 겉보리에 오염된 곰팡이와 곰팡이독소를 조사하였다. 저장 중 보리에 오염된 주요 곰팡이 속은 Fusarium, Epicoccum, Alternaria 및 Drechslera 이었다. 상온창고는 저장 후기로 갈수록 Fusarium 과 Alternaria 속 곰팡이가 큰 폭으로 감소한 반면 Drechslera는 증가하였다. 저온창고, 항온항습실 및 종자저장고에서는 Fusarium 오염립의 감소폭이 적었고 저장 6개월 후에도 2.5 log CFU/g 이상이 검출되었다. 니발레놀 오염은 한 시료에서 저장 0-3개월 간 비슷한 수준을 유지하다가 6개월 후 증가하였으며, 저장소 간 차이는 나타나지 않았다. 따라서 겉보리 저장 중 니발레놀 오염 예방을 위해 저장 기간을 6개월 미만으로 줄이는 것이 효율적일 것으로 보인다. To establish good storage practices for hulled barley against mycotoxin contamination, we measured occurrence of fungi and mycotoxin in hulled barley grains under various storage conditions. Hulled barley grains collected from two places were stored in five different warehouses: 1) two without temperature control, 2) one with temperature controlled at $12^{\circ}C$, 3) a chamber set at $15^{\circ}C/65%$ relative humidity, and 4) one seed storage set at $10^{\circ}C$. The samples were stored for six month with temperature and relative humidity monitored regularly. Every stored samples were retrieved after 0, 1, 3, and 6 month to investigate fungal and mycotoxin contamination. From the stored grains, Fusarium, Epicoccum, Alternaria, and Drechslera spp. were frequently detected. In the warehouses without temperature control, Fusarium and Alternaria spp. constantly decreased, whereas Drechslera spp. increased along with storage period. In the other warehouses with temperature controlled, Fusarium spp. decreased slowly and more than 2.5 log CFU/g of Fusarium spp. were detected after 6 month storage. The level of nivalenol was maintained during 0-3 month but increased after 6 month storage. There was no difference in the nivalenol levels between the warehouses. Therefore reducing storage period less than 6 months could be more effective to control nivalenol contamination in hulled barley grains.

Genomic Analysis of the Carrot Bacterial Blight Pathogen Xanthomonas hortorum pv. carotae in Korea

Mi-Hyun Lee,Sung-Jun Hong,Dong Suk Park,Hyeonheui Ham,공현기 한국식물병리학회 2023 Plant Pathology Journal Vol.39 No.4

Bacterial leaf blight of carrots caused by Xanthomonas hortorum pv. carotae (Xhc) is an important worldwide seed-borne disease. In 2012 and 2013, symptoms similar to bacterial leaf blight were found in carrot farms in Jeju Island, Korea. The phenotypic characteristics of the Korean isolation strains were similar to the type strain of Xhc. Pathogenicity showed symptoms on the 14th day after inoculation on carrot plants. Identification by genetic method was multi-position sequencing of the isolated strain JJ2001 was performed using four genes (danK, gyrB, fyuA, and rpoD). The isolated strain was confirmed to be most similar to Xhc M081. Furthermore, in order to analyze the genetic characteristics of the isolated strain, whole genome analysis was performed through the next-generation sequencing method. The draft genome size of JJ2001 is 5,443,372 bp, which contains 63.57% of G + C and has 4,547 open reading frames. Specifically, the classification of pathovar can be confirmed to be similar to that of the host lineage. Plant pathogenic factors and determinants of the majority of the secretion system are conserved in strain JJ2001. This genetic information enables detailed comparative analysis in the pathovar stage of pathogenic bacteria. Furthermore, these findings provide basic data for the distribution and diagnosis of Xanthomonas hortorum pv. carotae, a major plant pathogen that infects carrots in Korea.

First Report of Fire Blight Caused by Erwinia amylovora on Korean Mountain Ash (Sorbus alnifolia) in Korea

Lim Yeon-Jeong,Oh Hyeonseok,Lee Mi-Hyun,Roh Eunjung,Ham Hyeonheui,Park Dong Suk,박덕환,Lee Yong Hwan 한국식물병리학회 2023 식물병연구 Vol.29 No.1

During the nationwide survey of fire blight, the typical shoot blight symptoms were found on Korean mountain ash (Sorbus alnifolia) which was located near an orchard that produced fire blight on pear trees in Eumseong, Korea, May 2021. To identify the causal agent, we progressed isolation from the symptomatic leaves and shoots. Two white and mucoid colonies were isolated into the pure culture. Two isolates were identified as Erwinia amylovora according to the colony–polymerase chain reaction (PCR) with amsB primers and the phylogenetic tree using 16S rRNA sequences. To test of pathogenicity of two isolates, we inoculated immature pear fruits and understock of apple. We observed necrosis and oozes on immature pear fruits and shoot blight resulting in necrosis on apple shoots six days after inoculation. Colonies were recovered from the inoculated pears and apples, and identity was confirmed through colony PCR for amsB genes. To our knowledge, E. amylovora was first reported on Korean mountain ash native to South Korea.

블로워 모터 소음의 내구성 고찰

이명한(Myunghan Lee),이강덕(Kangduck Ih),황동우(Dongwoo Hwang),이현희(Hyeonheui Lee) 한국소음진동공학회 2007 한국소음진동공학회 학술대회논문집 Vol.2007 No.11