전국 미곡종합처리장에서 채집한 2009년산 쌀과 가공부산물 시료의 독소생성곰팡이 오염

류재기,손승완,이승호,이수민,이수형,김미자,이데레사,윤종철,남영주 한국식물병리학회 2011 식물병연구 Vol.17 No.3

This investigation was undertaken to survey toxigenic fungal contamination of various rice samples in 93 rice processing complexes (RPC) in Korea. Rice was grown in 2009 and the samples were collected in 2010. Seven types of rice samples such as unhusked, brown, blue-tinged, discolored, polished, half-crushed, and rice husks were obtained from each RPC. One-hundred and five grains of each sample were placed on PDA plates after surface disinfection. The incidence of fungal contaminants was 26.8%. Aspergillus spp. was the most dominant fungal contaminants and Fusarium spp. was the most frequently occurred in samples. The heaviest Fusarium contamination was found in unhusked grain, rice husks, and bare blue-tinged rice and followed by colored rice whereas broken rice was the least contaminated. Regional difference of fungal contamination was distinctive. Fusarium incidence in the rice samples from southern region of Korea including Jeolla and Gyeongsang Provinces was higher than those from central region including Chungcheong, Gyeonggi, and Gangwon Provinces. In contrast to Fusarium spp., Aspergillus spp. and Penicillium spp. were dominated in brown and polished rice samples and their incidences were more severe in central region than southern region. The major contaminants shown more than 1% of kernels infected were Aspergillus (5.0%), Fusarium (2.0%), Alternaria (1.4%), Dreschlera (1.3%), Penicillium spp. (1.3%), and Nigrospora spp. (1.0%). Collectotrichum,Pyricularia, Myrothecium, Epicoccum, Cladosporium, Moniliella, Gloeocercospora, Chaeto- mium,Curvularia, Phialopora, Acremonium, Gliomastix, Trichoderma, Rhizopus, Phomopsis, Paecilomyces,Genicularia, Geotrichum, Acremoniella, Rhizoctonia, Phoma, Oidiodendran, and Candida spp. were among the rest observed at low incidence. The major contaminants of rice samples were well-known as toxigenic fungal genera so toxin producibility of these fungal isolates is necessary to be examined in future. It is also needed to study Myrothecium spp. on species level as it was detected for the first time in rice. 본 연구에서 우리나라 미곡종합처리장의 가공단계별 7종의 쌀 시료에 대한 곰팡이 오염 정도를 조사하였다. 곰팡이독소를 생산하는 곰팡이인 Aspergillus spp., Fusarium spp., Penicillium spp., Alternaria spp.가 우점하고 있었고, 포장곰팡이인 Fusarium과 Alternaria는 남부지방에 저장곰팡이인 Aspergillus와 Penicillium는 중부지방에 오염이 많았다. 또한 원료벼에서 가공단계가 진전될수록 Fusarium과 Alternaria와 같은 포장곰팡이의 오염 정도는 낮아졌으나 심하게 오염된 전라도 시료에서는 크게 낮아지지 않는 경향을 보였다. Aspergillus와 Penicillium과 같은 저장 곰팡이의 오염 정도는 가공단계가 진전될수록 높은 경향을 보였다. 또한 7종의 쌀 시료에는 총 35종의 곰팡이 속(genus)이 오염되어 있었으며 이 중 Myrothecium spp.는 우리나라 쌀 시료에서 처음으로 검출되었다. 이러한 결과는 우리나라의 주식인 쌀의 수확 후 저장, 가공과정의 곰팡이독소의 오염을 종합적으로 관리하기 위한 기초 자료가 될 것이다.

GAP 활성화를 위한 기술적 지원체계 구축방안

류재기 한국농약과학회 2015 한국농약과학회 학술발표대회 논문집 Vol.2015 No.4

희소방선균 SeaR 유전자가 Streptomyces virginiae의 virginiamycins 생산에 미치는 영향

류재기,김현경,김병원,김동찬,이형선,Ryu, Jae-Ki,Kim, Hyun-Kyung,Kim, Byung-Won,Kim, Dong-Chan,Lee, Hyeong-Seon 한국미생물학회 2015 미생물학회지 Vol.51 No.3

본 연구는 희소방선균 Saccharopolyspora erythreae receptor gene (SeaR)의 기능을 연구하기 위해 다른 속의 균주인 Streptomyces virginiae에 SeaR 유전자를 도입하였다. S. virginiae의 형질전환은 oriT, attP, $ermEp^{\ast}$과 SeaR 유전자 단편을 가지고 있는 ${\varphi}C31$ 유래의 integration vector인 pEV615 (6.6 kb)를 이용하여 Escherichia coli ET12567/pUZ8002를 DNA 공여체(donor)로 이용한 접합전달법(conjugal transfer)을 사용하여 확립하였다. SeaR 유전자의 삽입 유무는 PCR방법으로 확인하였고, SeaR 유전자의 전사 발현은 RT-PCR방법으로 확인하였다. S. virginiae의 경우, virginiamycins 생산은 wild type (S. virginiae)와 transformants (C1, C3) 모두 최초생산시기가 14시간으로 같았다. $VB-C_6$ 첨가시기에 따른 항생물질 유도능 확인결과 본 배양 4시간에 $VB-C_6$ 첨가 시 wild type과 transformants (C1, C3) 모두 $VB-C_6$에 의한 virginiamycins 생성이 유도되지 않았다. 본배양 6시간, 8시간에 $VB-C_6$ 첨가하였을 시 $VB-C_6$에 의한 virginiamycins 생성이 유도되는 것을 확인하였다. 이 결과는 $VB-C_6$에 의한 유도의 경우 S. virginiae 내의 BarA에 의해 VMs 생산시기가 2-4시간 단축되었다고 사료되나, transformants C1, C3의 경우 $VB-C_6$ 첨가 시 virginiamycins 생산이 억제되는 것은 SeaR이 virginiamycins 생합성 유전자에 결합하여 억제자로 기능 한다고 추정 되었다. 이러한 결과로 인하여 외부에서 도입된 SeaR gene이 virginiamycins 생산에 영향을 주는 것으로 확인되었다. In order to study the effect of the receptor protein (SeaR), which is isolated from Saccharopolyspora erythraea, we introduced the SeaR gene to Streptomyces virginiae as host strains. An effective transformation procedure for S. virginiae was established based on transconjugation by Escherichia coli ET12567/pUZ8002 with a ${\varphi}C31$-derived integration vector, pSET152, which contained int, oriT, attP, and $ermEp^{\ast}$ (erythromycin promotor). Therefore, the pEV615 was introduced into S. virginiae by conjugation and integrated at the attB locus in the chromosome of the recipients by the ${\varphi}C31$ integrase (int) function. Transformants of S. virginiae containing the SeaR gene were confirmed by PCR and transcriptional expression of the SeaR gene in the transformants was analyzed by RT-PCR, respectively. And, we examined the production time of virginiamycins in the culture media of both the transformants and the wild type. The production time of virginiamycins in the wild type and transformants was the same. When 100 ng/ml of synthetic $VB-C_6$ was added to the state of 6 or 8 hour cultivation of wild type and transformants, respectively, the virginiamycins production was induced, meaning that the virginiamycins production in the wild type was detected 2 h early than transformants. From these results, SeaR expression was also affected to virginiamycins production in transformants derived from S. virginiae. In this study, we showed that the SeaR protein worked as a repressor in transformants.

김천시내 약수의 보관일수에 따른 미생물조사 연구

류재기 김천대학교 2009 김천대학교 논문집 Vol.30 No.-

A microbial experiment was conducted at four mineral springs where manypeople use in Gimcheon city, in order to prevent water-borne disease and supplyclean water. This experiment was also conducted to set up a standardization ofdrinkable period in both cold storage and room temperature storage. After observ-ing the number of bacterial colonies for 7 days, the appropriateness of drinkablewater was examined. This research was done in a germfree condition. When this water was drunkenin the home the drinkable time of this water can be more advanced than the results.From the results of the test of spring water in Gimcheon there was no significantdifference between the water of cold storage and the water of the room tempera-ture storage. But after 7 days in the room temperature the spring water of WongukMaul was evaluated as unfit on 6th day. From 7th day except Mt. Dalbong everyspring water was evaluated as unfit. In the case of cold storage keeping from 7thday except Mt. Dalbong every spring water was evaluated as unfit. A sample mineral springs were collected from a total of four locations, and gramnegative bacilli, general bacteria and Fungus were detected from all of the fourplaces. In the case of 3-5 day storage, it turned out that all the places were notsafe from drinking except Mt. Dalbong. Therefore, it is considered that it will besafe to drink mineral water within five days in cold storage and to settle expirationdate. This research was done in an aseptic condition, when this water was drunken inthe home the drinkable time of this water can be more advanced than the results.

2010년산 맥류의 붉은곰팡이병 발생 및 Fusarium 곰팡이독소 자연발생

류재기,이수형,손승완,이승호,남영주,김미자,이데레사,윤종철 한국식물병리학회 2011 식물병연구 Vol.17 No.3

Fusarium species are worldwide causal agents of Fusarium head blight (FHB) in cereals such as barley and wheat. Their toxigenic potential is a health risk for both humans and animals. To survey the natural occurrence of FHB and mycotoxins produced by Fusarium, total 126 barley or wheat grains grown in 2009-2010 season in Korea were collected. The incidence of FHB was 30.7% in silage barley, 26.9% in wheat,20.7% in naked barley, 19.4% in malting barley, 16.4% in unhulled barley. Overall FHB incidence of barley and wheat in 2010 was 23.0% and 10% higher than that of 2009. The incidences and level of deoxynivalenol (DON), nivalenol (NIV), and zearalenone (ZEA) were 34%, 0.89 mg/kg, 84.9%, 1.86 mg/kg, and 10.3%, 0.06mg/kg respectively. The both levels and incidences of NIV were found to be highest in barley, whereas the level of DON was found to be highest in wheat. Incidences of DON and NIV and the level of NIV in the samples from southern regions of Korea were higher than those from central region, whereas the level of DON from central region was higher than that from southern regions. This is the first paper demonstrating regional difference in natural occurrence of DON and NIV in wheat and barley. 2010년산 쌀보리 43시료, 겉보리 17시료, 맥주보리 11시료, 청보리 14시료, 밀 41시료 등 총 126개 시료를 농가로부터 채집하였다. 이들 시료를 대상으로 Fusarium균 오염정도와 이들 균이 생산하는 주요 독소인 DON, NIV, ZEA의 자연발생을 조사하였다. 2010년산 맥류의 전국 평균 오염율은 23.0%로 2009년 전국 평균 오염율(Yeh 등, 2010)에 비해 10% 이상 높았다. 지역별 오염율은 전남지방의 맥류가 35.8%로 가장 높았고 전북 20.8%, 경기 20.5% 순이었다. 각 독소별 오염빈도와 오염수준을 조사한 결과, DON은 43시료(34%), 0.89 mg/kg 이었고, NIV는 107시료 (84.9%), 1.86 mg/kg, ZEA은 13시료(10.3%), 0.06 mg/kg이 었다. NIV의 오염빈도가 DON과 ZEA에 비해 높았다. 한편 40시료(31.7%)가 DON과 NIV가 중복오염되어 있었다. 맥류 종류별 곰팡이독소의 오염수준을 보면, 밀에서는 DON의 오염수준이 NIV보다 높았으며, 보리에서는 NIV 오염수준이 DON보다 높았다. 보리 종류별 NIV의 오염수준은 청보리, 맥주보리, 쌀보리, 겉보리 순으로 높았다. 독소오염에 대해 지역별로 분석하여보면 경기, 충남북의 중부지방은 DON의 오염수준이 NIV보다 높았으며, 전남북과 경남북의 남부지방은 NIV의 오염수준이 높았다. DON과 NIV 독소의 오염빈도 또한 중부지방에 비해 남부지방이 많았다. 지역별 맥류 곰팡이독소 자연발생 양상의 차이를 처음으로 보고한다.

한국산 보리로부터 분리한 Fusarium균주가 생성하는 진균독소

류재기,이인원 한국식물병리학회 1990 Plant Pathology Journal Vol.6 No.1

희소방선균의 seaR 단백질 발현을 통한 기능 분석

류재기,권필승,이형선,Ryu, Jae Ki,Kwon, Pil-Seung,Lee, Hyeong Seon 한국미생물학회 2015 미생물학회지 Vol.51 No.1

방선균이 생산하는 이차대사산물은 자기조절인자(${\gamma}$-butyrolactone autoregulator)라고 불리는 저분자의 신호전달물질과 이에 특이적으로 결합하는 autoregulator receptor protein의 상호작용에 의해 조절되는 것으로 알려져 있다. 그러므로 non-host에 autoregulator receptor 혹은 pleiotropic regulator의 발현은 이차대사산물 혹은 새로운 대사화합물의 효율적인 생산을 유도할 것으로 기대된다. 희소방선균 Saccharopolyspora erythreae으로부터 receptor (seaR) 유전자의 기능을 연구하기 위해 다른 속의 균주인 Streptomyces coelicolor A3(2)로 seaR 유전자를 삽입하여 형질전환하였다. S. coelicolor A3(2)의 형질전환은 oriT, attP, $ermEp^*$과 seaR gene 단편을 가지고 있는 ${\Phi}C31$ 유래의 integration vector인 pEV615 (6.6 kb)를 이용하여 Escherichia coli ET12567/pUZ8002를 DNA 공여체로 이용한 접합전달법을 사용하여 확립하였다. seaR 유전자의 삽입 유무는 PCR방법으로 확인하였고, seaR 유전자의 전사 발현은 RT-PCR방법으로 확인하였다. S. coelicolor A3(2)의 경우 표현형 microarray 실험을 통하여 seaR 유전자의 발현에 따른 표현형의 변화를 확인하였다. 특히, 표현형 microarray 실험에 나타난 tetracycline 항생제 기질에 대하여 wild type이 transformant에 비해 빠르게 성장하는 것은 항균제 감수성 검사와 일치하였다. 이는 tetracycline 생합성 유전자 및 내성 유전자의 발현 억제에 따른 변화라고 예상할 수 있으며 이를 위하여 tetracycline 생합성 관련 유전자 및 내성 유전자의 발현 패턴 분석등과 같은 분자 수준에서의 연구가 필요할 것으로 생각된다. Secondary metabolism in actinomycetes has been known to be controlled by a small molecule, ${\gamma}$-butyrolactone autoregulator, the binding of which to each corresponding receptor leads to the regulation of the transcriptional expression of the secondary metabolites. We expected that expression of an autoregulator receptor or a pleiotropic regulator in a non-host was to be gained insight of effective production of new metabolic materials. In order to study the function of the receptor protein (seaR), which is isolated from Saccharopolyspora erythraea, we introduced the seaR gene to Streptomyces coelicolor A3(2) as host strains. An effective transformation procedure for S. coelicolor A3(2) was established based on transconjugation by Escherichia coli ET12567/pUZ8002 with a ${\varphi}C31$-derived integration vector, pSET152, which contained int, oriT, attP and $ermEp^*$ (erythromycin promotor). Therefore, the pEV615 was introduced into S. coelicolor A3(2) by conjugation and integrated at the attB locus in the chromosome of the recipients by the ${\varphi}C31$ integrase (int) function. Exconjugant of S. coelicolor A3(2) containing the seaR gene was confirmed by PCR and transcriptional expression of the seaR gene in the transformant was analyzed by RT-PCR. In case of S. coelicolor A3(2), a phenotype microarray was used to analyze the phenotype of transformant compared with wild type by seaR expression. After that, in order to confirm the accuracy of the results obtained from the phenotype microarray, an antimicrobial susceptibility test was carried out. This test indicated that sensitivity of the transformant was higher than wild type in tetracycline case. These results indicated that some biosynthesis genes or resistance genes for tetracycline biosynthesis in transformant might be repressed by seaR expression. Therefore, subsequent experiments, analysis of transcriptional pattern of genes for tetracycline production or resistance, are needed to confirm whether biosynthesis genes or resistance genes for tetracycline are repressed or not.

Incidence and Distribution of Virus Diseases on Paprika (Capsicum annuum var. grossum) in Jeonnam Province of Korea

류재기,이용환,김미경,김국형,김흥태,최홍수,Sug-Ju Ko 한국식물병리학회 2009 Plant Pathology Journal Vol.25 No.1

The incidence and occurrence of virus infecting paprika (Capsicum annuum var. grossum) in Jeonnam province, the main areas of cultivation in Korea is undetermined. In this study, a total of 1,020 samples with virus-like symptoms were collected in Jeonnam province during summer season for 3 consecutive years (2002-2005) and were tested using enzyme linked immunosorbent assay (ELISA). Results showed that Pepper mottle virus (PepMoV), Broad bean wilt virus (BBWV), and Cucumber mosaic virus (CMV) were found to be the most prevalent viruses with a 3-year average percent incidence of 41.3, 19.8, and 4.4 respectively. Mixed infection with more than two viruses was also found with 3.5%, 17.0%, and 8.3%, respectively. Symptoms of these virus diseases were not evident at the seedling stage but slowly appeared at the transplanting stage and increased to the middle stage (4-5 months after transplanting) during the 3-year cultivation periods. Symptom appearance of infected plants however varied largely with transplanting time. Those plants transplanted from November to January were found to be infected with viruses in June, whereas symptoms appeared with in a month those plants transplanted from June to August. There were differences in the virus incidence from primary factor such as district, type of green house and variety, but these were not statistically significant (data not shown). Recommended control measures of paprika against these viruses is also discussed in this paper.

기획특집 : 미생물학적 안전관리 R&D를 통한 GAP 농산물 공급확대

류재기 ( Jae Gee Ryu ),김황용 ( Hwang Yong Kim ),김세리 ( Se Ri Kim ),이데레사 ( Theresa Lee ),정규석 ( Ku Suk Jung ),김원일 ( Won Il Kim ) 한국식품위생안전성학회 2013 Safe Food Vol.8 No.4

대학생들의 콘텍트렌즈 저장용기의 미생물 오염도 조사

류재기, 장철수, 김현경 김천대학교 2013 김천대학교 논문집 Vol.33 No.-

The use of contact lenses is currently increasing because of a various consumers requirements such as those related to treatment and cosmetic issues. The increase in the number of contact lens users has been accompanied by eye infection due to improper han-dling of contact lenses. Therefore, this study was performed to determine the contamina-tion levels of lens storage cases, which can be an important cause of contamination of con-tact lenses, the cases belonged to students from the Department of Biomedical LaboratoryScience, Gimcheon University. A total of 62 lens storage cases were used in this study, and our results showed that 63% (39 cases) were contaminated with microorganisms. Stenotrophomonas maltophilia, Serratia marcescens, Achromobacter denitrificans, and fungi were detected in 8%, 10%, 72%, and 10%, respectively, of the cases. Stenotrophomonas maltophilia is a non-pathogenic bacterium; however, it is resistant to several antibiotics and is thought to cause endocarditis and meningitis. Eye infection with Serratia marcescens can lead to microbial keratitis and contact lens-induced acute red eye, particularly during overnight contact lens wear. Fungal eye infection is characterized by eye redness, pain, excessive tears formation and blurred vision. In conclusion, the results, which showed that a high proportion of the contact lens storage cases studied were contaminated with bacteria and fungi, suggest that providing proper education regarding the use and storage of contact lenses is important to prevent contact lens-induced eye infection.