• Food Science and Preservation
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• v.19 no.5
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• pp.757-766
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• 2012

The SSH100-10 bacterial strain, which exhibits strong antifungal (anti-mold and anti-yeast) activity, was isolated from traditional korean soysauce aged 100 years. The strain was identified as Bacillus velezensis based on Gram-staining, the biochemical properties and 16S rRNA gene sequence determination. B. velezensis SSH100-10 showed strong proteinase activity and NaCl tolerance, but did not produce enterotoxin. Two-antifungal compounds from B. velezensis SSH100-10 were purified using SPE, preparative HPLC, and reverse phase-HPLC. The purified antifungal compounds were identified as $C_{14}$ and $C_{15}$ iturin through MALDI-TOF-MS and amino acid composition analysis. The stability characteristics of the antifungal compounds after temperature, pH, and enzyme treatments suggested that B. velezensis SSH100-10 produced more than two antifungal compounds; pH-stable $C_{14}$ iturin A and $C_{15}$ iturin A, and unidentified pH-unstable compounds. The results suggested that B. velezensis SSH100-10 can be used in soybean fermentation as a starter. Moreover it has potential as a biopreservative in the food and feed industry and as a biocontrol agent in the field of agriculture.

• Korean Journal of Food Science and Technology
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• v.38 no.2
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• pp.309-312
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• 2006

Aflatoxin $B_1$ in 70 retail samples, including 40 food-grade peanut (28 domestic, 12 imported) and 30 peanut butter (12 domestic, 18 imported) samples, was analyzed by high-performance liquid chromatography (HPLC) with fluorescence detection (FD), and positive samples were confirmed using HPLC with mass spectrometry (MS). Recoveries of aflatoxin $B_1$ spiked at 2 ppb exceeded 80% in both commodities. Detection limits for aflatoxin $B_1$ by HPLC-FD and MS analysis were 0.8 and 0.1 ppb, respectively. Four domestic and six imported peanut samples contained detectable levels of aflatoxin $B_1$ with means of 19 and 32 ppb, respectively. Aflatoxin $B_1$ was found in two domestic and three imported peanut butter samples with mean aflatoxin $B_1$ of 10 and 12 ppb, respectively. Peanut commodity showed more frequent aflatoxin $B_1$ contamination compared to its processed peanut butter product, and levels of aflatoxin $B_1$, especially in imported peanuts, were significantly (p<0.05) higher than those of other commodities. These results suggest peanut and peanut butter are not major contributors to dietary intake of aflatoxin $B_1$ in South Korea.

• Korean Journal of Food Science and Technology
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• v.30 no.6
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• pp.1415-1419
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• 1998

In order to evaluate the safety of greenhouse horticultures, a large number sample sources were collected, and the fungi of Aspergillus sp. and Penicillium sp. were isolated from them. Indirect competitive ELISA method and high performance liquid chromatography (HPLC) were applied to confirm the ochratoxin A producing abilities of isolated strains. One hundred ninety two sample sources including soil, pepper, strawberry and water mellon were collected for fungi isolation from western Gyeongnam, Andong and Gyeongbok. One hundred forty two strains of Aspergillus sp. and one hundred fifty three strains of Penicillium sp. were isolated respectively from them. The isolated fungi were tested for the production of ochratoxin A by ELISA. After culture of them on the modified sucrose low salt medium at $28^{\circ}C$ for 15 days, we found that five strains of Penicillium sp. produced ochratoxin A at the levels of $0.084{\sim}2.128\;{\mu}g/mL$. Among them, #129-2 strain isolated from water melon, showed the highest level of ochratoxin A as $2.128\;{\mu}g/mL$ broth. However, all of isolated Aspergillus sp. didn't produce ochratoxin A. When we compared the results of ELISA method with HPLC method, ochratoxin A production of each isolated strains showed very similar levels.

• Journal of Veterinary Clinics
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• v.24 no.2
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• pp.82-87
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• 2007

Five dogs with renal failure were referred to the Veterinary Medical Teaching Hospital at Kangwon National University. These dogs had the common history of consumption of Pedigree dry dog food produced in Thailand plant for over 1 month. The dogs showed anorexia, emaciation, vomiting, and polydipsia/polyuria. And in one severely affected dog, bloody diarrhea and hypothermia were seen. The remarkable clinicopathological signs were high value of BUN and creatinine. In some dogs, GGT, phosphorus and lipase were increased. However, no significant changes of complete blood count were found. In urinalysis, hematuria, low specific gravity urine, proteinuria, and calcium oxalate-like crystals were observed. Two severely affected dogs were died. The remained dogs were recovered gradually after change of dog food and supportive therapy. Pathological findings were seen typically in kidneys. Renal atrophy, congestion of the glomerular capillary, and diffuse degeneration, necrosis, dystrophic calcification and regeneration in the tubular epithelium were seen. Yellowish brown fluorolucent laminated materials or particles were quite often found in the lumina of the necrotizing renal tubules of cortex and medulla. Proliferation of fibrous tissue in the interstitium was also seen. By the mycotoxin analysis of the Pedigree dry dog food, ochratoxin A (OTA) and citrinin were detected as much as the concentration of 372.8 ppb and 8.3 ppb, respectively. The final diagnosis of renal failure caused by OTA and citrinin toxicosis was made on the basis of history takings, clinical signs, clinicopathological and pathological findings, and analysis of mycotoxins.

• Journal of Food Hygiene and Safety
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• v.34 no.3
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• pp.269-276
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• 2019

A colorimetric rapid detection method based on acetylcholinesterase (AChE) was developed for the analysis of organophosphorus (OP) and carbamate (CB) pesticides. The AChE catalyzes acetylthiocholine into thiocholine having (-) and (+) charges, and the (+) charge results in gold nanoparticle (GNP) aggregation. The in-activation of AChE by OP and CB has been well known. In order to optimize the colorimetric method, optimal dilution times of commercial serum containing AChE, diameter of GNP, and concentration of acetylthiocholine were tested as a key parameter. The colorimetric detection limits of the method were 7.5 ng/mL for both dimethyl amine and carbofuran pesticides in 60% ethanol. No cross-reaction to other chemicals, such as aflatoxin B1 and ochratoxin A, which can be contaminated with pesticides in agricultural products, was observed. Recoveries from lettuce, sesame leaf, and cabbage lettuce spiked with known concentrations of dimethyl amine and carbofuran were found to be ranged from 83.85 to 133.16%. These results indicated that the colorimetric rapid method based on AChE can be a useful tool for the sensitive, specific, rapid, and accurate detection of OP and CB pesticides in fresh vegetables.

• Korean Journal of Pharmacognosy
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• v.53 no.3
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• pp.162-169
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• 2022

This study investigated the mycotoxins (aflatoxin B₁, B₂, G₁, G₂, fumonisin B₁, B₂, ochratoxin A and zearalenone) contained in edible and medicinal plants in Seoul Yangnyeong market during 2020-2021. We analyzed contamination of mycotoxins using LC-MS/MS and evaluated risk assessment. The method was validated by assessing matrix effects, linearity, limit of detection (LOD), limit of quantification(LOQ) and recovery. Matrix-matched standard calibration was used for calibration curves showed good linearity (r²>0.999). The LOD, LOQ and recovery were 0.01-0.23 ㎍/kg, 0.04-0.71 ㎍/kg and 75.5-117.9% respectively. Mycotoxins were detected in 22 of 171 samples; aflatoxin B₁ (6.66 ㎍/kg), fumonisin (7.54-64.68 ㎍/kg), ochratoxin A (4.21-10.56 ㎍/kg) and zearalenone (7.31-60.76 ㎍/kg). In the risk assessment, the MOE (Margine of Exposure) of aflatoxin B₁ and ochratoxin A were in the range of 1.48×10³-2.36×10⁵. No items exceeded 100% in %TDI (Tolerable Daily Intake) of fumonisin (B₁+B₂) and zearalenone.

• Research in Plant Disease
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• v.28 no.1
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• pp.19-25
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• 2022

Ginseng is an important medicinal plant cultivated in East Asia for thousands of years. It is typically cultivated in the same field for 4 to 6 years and is exposed to a variety of pathogens. Among them, ginseng root rot is the main reason that leads to the most severe losses. In this study, endophytic bacteria were isolated from healthy ginseng, and endophytes with antagonistic effect against ginseng root rot pathogens were screened out. Among the 17 strains, three carried antagonistic effect, and were resistant to radicicol that is a mycotoxin produced by ginseng root rot pathogens. Finally, Bacillus velezensis CH-15 was selected due to excellent antagonistic effect and radicicol resistance. When CH-15 was inoculated on ginseng root, it not only inhibited the mycelial growth of the pathogen, but also inhibited the progression of disease. CH-15 also carried biosynthetic genes for bacillomycin D, iturin A, bacilysin, and surfactin. In addition, CH-15 culture filtrate significantly inhibited the growth and conidial germination of pathogens. This study shows that endophytic bacterium CH-15 had antagonistic effect on ginseng root rot pathogens and inhibited the progression of ginseng root rot. We expected that this strain can be a microbial agent to suppress ginseng root rot.

• Journal of Mushroom
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• v.9 no.4
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• pp.180-185
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• 2011

Spent mushroom substrates (SMS) is a by-product remaining after a crop of mushrooms. About four surfactin-producing strains were isolated from SMS (Pleurotus eryngii). Among of them, one isolate, which designated to YJ07, potentially showed the antifungal activity against Aspergillus flavus and Aspergillus ochraceous producing mycotoxin on PDA medium. The biochemical characteristics of the strain YJ07 was similar with Bacillus subtilis and Bacillus amyloliquefaciens by Bacillus ID kit and VITEK 2 system. Comparative 16S rDNA gene sequence analysis of the strain YJ07 also showed that the strain YJ07 was most closely related to Bacillus amyloliquefaciens with sequence similarity of 99.5%. On the basis of their biochemical characteristics and phylogenetic distinctiveness, the strain YJ07 was classified within the genus Bacillus as Bacillus amyloliquefaciens YJ07. The antifungal compound from B. amyloliquefaciens YJ07 was similar to lipopeptide surfactin from Bacillus subtilis by TLC and HPLC analysis.

• Journal of Food Hygiene and Safety
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• v.35 no.1
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• pp.1-5
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• 2020

Foodborne diseases (FBD) pose significant public health problems and economic losses worldwide. In recent years, emerging foodborne diseases have resulted mainly from novel bacteria, viruses, protozoa, mycotoxins, prions in animal and plant sources. The consumption of unsafe food contaminated with harmful bacteria, viruses, parasites or chemical agents or naturally occurring toxins results in high morbidity and mortality. However, estimating the incidence and burden of FBD is a huge global challenge due to the difficulty in food source attribution to specific pathogenic or chemical hazards, underreported cases, diagnosing how infections are transmitted or when a person is infected are not well understood and thus makes the control of FBD very challenging. Therefore, implementing comprehensive food safety strategies and policies, enhancing surveillance, ensuring resilient health system, and intensifying education and training to ensure safe food and prevent foodborne diseases is everybody's responsibility.

• Journal of Food Hygiene and Safety
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• v.37 no.2
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• pp.87-96
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• 2022

Recently, the purchase of fresh-cut produce and meal kits has increased. Ready-to-eat (RTE) fresh-cut products have potentially hazard of cross-contamination of various microorganisms in the processes of peeling, slicing, dicing, and shredding. There are frequent cases of protozoa food poisoning, such as Cyclospora and Cryptosporidium, caused by fresh-cut products. The objective of the study is to investigate the microbiological qualities of various types of RTE fresh-cut products in the domestic on/offline markets. RTE fresh-cut fruits cup (n=100), fresh-cut vegetables (n=50), and vegetables in meal kits (Vietnamese spring rolls and white radish rolls kits, n=50) were seasonally analyzed. The contamination levels of hygienic indicator organisms, yeast and mold (YM), and foodborne pathogens (Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Salmonella spp., and Escherichia coli O157:H7) were monitored. Overall, the lowest microbiological qualities of meal kits vegetables were observed, followed by RTE fresh-cut fruits cup and fresh-cut vegetables. Contamination levels of total aerobic bacteria, coliforms, and YM in meal kits vegetables were 5.91, 3.90, and 4.71 logs CFU/g, respectively. From the qualitative analysis, 6 out of 200 RTE fresh-cut products (3%) returned positive result for S. aureus. From the quantitative analysis, the contamination levels of S. aureus in purple cabbage from a meal-kit and fresh-cut pineapple were below the acceptable limit (100 CFU/g). Staphylococcus enterotoxin seg and sei genes were detected in RTE fresh-cut celery and red cabbage from meal-kits, respectively. S. aureus contamination must be carefully controlled during the manufacturing processes of RTE fresh-cut products. Neither Cyclospora cayetanensis nor Cryptosporidium parvum was detected in the samples of RTE fresh-cut products and vegetables from meal-kits from the Korean retail markets.