• KOREAN POULTRY JOURNAL
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• v.8 no.6 s.80
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• pp.92-96
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• 1976

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.5
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• pp.674-680
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• 2009

The objective of this study was to investigate antimicrobial activity, during the storage period, of animal feed and any effects on in vitro rumen digestion by supplementing different levels (5.55, 11.1, and 22.2 g/kg) of freeze dried citrus peel (FDCP) to the feed compared to untreated feed and feed treated with an antifungal agent (AA) at 0.05 g/kg. In a preservation test, feed supplemented with FDCP showed no deterioration over 21 days. Untreated feed and AA-treated feed, however, showed signs of deterioration after 16 days storage. Yellow colour and red colour, measured by spectro chromameter, decreased in the untreated and AA-treated feeds, but not in feed supplemented with FDCP. Aflatoxin was detected in untreated and AA-treated feeds at 16 days (8 ppb and 2 ppb) and 21 days (8 ppb and 4 ppb), but aflatoxin was not detected in the feed supplemented with FDCP. In a second experiment, fermentation by rumen microorganisms of FDCP (22.2 g/kg) and AA (0.05 g/kg) supplemented feeds was studied in vitro. Feeds were incubated with buffered rumen fluid for 3, 6, 9, 12, 24, and 48 h. Dry matter digestibility (DMD) and organic matter digestibility (OMD) were affected by treatment, but ammonia-N, total, and individual volatile fatty acids (VFA) were not adversely affected by treatment. In conclusion, the results indicated that FDCP might be useful for inhibiting microbial growth of animal feed during storage without disrupting rumen fermentation.

• Research in Plant Disease
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• v.18 no.4
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• pp.261-267
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• 2012

Inspection of deteriorated rices in Korea for fungal occurrence revealed that Aspergillus was the most frequently observed genus and some isolates of the Aspergillus spp. turned out to produce aflatoxin. Diverse fungal genera including Fusarium, Aspergillus, Penicillium, or Alternaria spp. were observed in most of the rice samples. Aflatoxin occurred infrequently and the levels of aflatoxin present in the rice samples were lower than regulatory limit but Fusarium toxins such as deoxynivalenol, nivalenol, zearalenone, and fumonisin occurred frequently. In rice processing complexes, fungal and mycotoxin contamination of rice decreased by milling process, resulting in the lowest level of mycotoxin and fungi in polished rice. Currently, it appears that Korean rice and milled by-products need a safety control for Fusarium toxins rather than aflatoxin.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.11
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• pp.1617-1622
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• 2006

Long-term storage of feeds or feedstuffs in high temperature and humid conditions can be difficult because of microbial contamination. Essential oil isolated from industrial waste citrus peel could be used as a preservative because it is likely to have anti-bacterial and anti-fungal activity. Our objective was to determine whether different levels (0.028, 0.056 and 0.112 g/kg) of citrus essential oil (CEO) would provide anti-microbial activity and enhance preservation of animal feed without influencing rumen fermentation. At 0.112 g/kg, CEO inhibited growth of Escherichia coli (ATCC 25922) and Salmonela enteritidis (IFO 3313). Growth of E. coli recovered after 24 h of incubation, but S. enteritidis continued to be inhibited for 72 h. Preservation of antibiotic-free diets for swine was assessed by observing anti-aflatoxin activity. Aflatoxin was detected in control feed samples on days 16 (8 ppb) and 21 (8 ppb) and in anti-fungal agent (AA) treated samples on days 16 (2 ppb) and 21 (4 ppb). However, aflatoxin was not detected in feed samples treated with CEO. Treatment with CEO and AA did not influence ruminal pH, dry matter digestibility (DMD) or organic matter digestibility (OMD) over 48 h of incubation in rumen fluid. Acetate and propionate were slightly higher with CEO treatment (p<0.05), but total concentration of volatile fatty acid (VFA) was not significantly affected by treatment. Ammonia-N concentration was slightly higher for the control treatment (p<0.05). This study showed that treating feed with CEO enhances preservation of animal feed without influencing in vitro rumen fermentation.

• 한국균학회소식:학술대회논문집
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• 2014.05a
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• pp.25-25
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• 2014

Koji molds are comprised of yellow, black and white. Black and white koji molds were recently re-visited by this author and it is concluded that they consists of Aspergillus luchuesnsis, A. niger and A. tubingensis, and the most important species for alcoholic beverage production is A. luchuensis. In the case of yellow koji mold, it is comprised of Aspergillus oryzae, A. sojae and A. tamari. In the case of A. sojae, the species is scarcely isolated from nature and rarely used for industry in Korea. Aspergillus tamari is often isolated from traditional Korean Meju, a fermented soybean product, and the classification of the species is clear. However, in the case of A. oryzae, differentiation between A. oryzae and A. flavus is still in controversy. In this study, we collected 415 strains of Aspergillus flavus/oryzae complex from air, rice straw, soybean, corn, peanut, arable soil and Meju in Korea and we examined the aflatoxin producing capacity of the strains. The norB-cypA, omtA and aflR genes in the aflatoxin biosynthesis gene cluster were analyzed. We found that 367 strains (88.4%) belonged to non-aflatoxigenic group (Type I of norB-cypA, IB-L-B-, IC-AO, or IA-L-B- of omtA, and AO type of aflR), and only 48 strains (11.6%) belonged to aflatoxin-producible group (Type II of norB-cypA, IC-L-B+/B- or IC-L-B+ of omtA, and AF type of aflR). In the case of A. flavus/oryzae strains from Meju, almost strains (178/192, 92.7%) belonged to non-aflatoxigenic group and only 14 strains (7.3 %) belonged to aflatoxin-producible group. It is proposed in this study that non-aflatoxigenic strain from Meju is classified as A. oryzae, considering that Meju is food material.

• Microbiology and Biotechnology Letters
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• v.18 no.5
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• pp.466-470
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• 1990

Aflatoxin $B_1$ ($AFB_1$) was reacted with ascorbic acid (AA) alone, with AA plue cysteine and with AA plus cupric ion for 5 days (at $37^{\circ}C$ and pH 5), and the mutagenicity of the reaction products was tested with Salmonella typhimurium TA 100. About 10% of AFBl induced mutagenesis was reduced when $AFB_1$ reacted with AA. This decreasing effect was more severe when $AFB_1$ reacted with AA plus cysteine. The mutagenicity of $AFB_1$ when reacted with AA plus cupric ion was almost completely inhibited, however, eupric ion itself was shown to enhance the mutagenicity of $AFB_1$. Therefore, $AFB_1$ may be degraded in the presence of AA under the given reaction condition and the reaction products was observed to have nonmutagenic effects on the bacterial mutagenecity trials.

• The Plant Pathology Journal
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• v.26 no.2
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• pp.121-129
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• 2010

We evaluated microbial populations and aflatoxin production in unhulled and white rice from rice processing complexes of the National Agricultural Cooperative Federation in five regions in Korea and identified three predominant Aspergillus species. Fungal and bacterial populations in rice samples were significantly different between regions in 2007. Aflatoxins were also detected and varied at the levels of 2.45 - 3.43 ng per g unhulled rice grain and 1.29 - 2.09 ng per g white rice grain. Unhulled rice generally detected higher level of aflatoxins than white rice regardless of sampling regions; however, no significant differences were found in Anseong and Cheonan in 2005 and Cheonan and Gimpo in 2007. Aflatoxin production between sampling regions was not different regardless of rice type and sampling year. Although the fungal diversity was highly distinct from region to region, three Aspergillus isolates were predominant in the rice samples; thus, representative isolates AC317, AF57, and AF8 were selected and identified based on their morphological and molecular characteristics. Consequently, isolates AC317, AF57, and AF8 were identified as A. candidus, A. flavus, and A. fumigatus, respectively. These fungi can produce mycotoxins that are harmful for consumers and thus it is important to detect and reduce the population of storage fungi in rice.

• Journal of Microbiology and Biotechnology
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• v.17 no.10
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• pp.1629-1637
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• 2007

An immunochromatography (ICG) strip test using a nanocolloidal gold-antibody probe was developed and optimized for the rapid detection of aflatoxin B1 (AFB1). A monoclonal antibody specific to AFB1 was produced from the cloned hybridoma cell (AF78), coupled with nanocolloidal gold, and distributed on the conjugate pad of the ICG strip test. The visual detection limit of the ICG strip test was 0.5 ng/ml, and this method showed a cross-reaction to aflatoxin B2, G1, and G2. In total, 172 grain and feed samples were collected and analyzed by both the ICG strip test and HPLC. The results of the ICG strip test showed a good agreement with those obtained by HPLC. These results indicated that the ICG strip test has a potential use as a rapid and cost-effective screening tool for the determination of AFB1 in real samples and could be applied to the preliminary screening of mycotoxin in food and agricultural products, generating results within 15 min without complicated steps.

• Journal of Microbiology and Biotechnology
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• v.30 no.8
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• pp.1207-1213
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• 2020

Aflatoxin B1 (AFB1) is a mycotoxin produced by Aspergillus flavus (A. flavus). AFB1 is reported to have high thermal stability and is not decomposed by heat treatment during food processing. Therefore, in this study, knowing that AFB1 is metabolized by cytochrome P450 (CYP), our aim was to develop a method to detoxify A. flavus-contaminated maize, under normal temperature and pressure, using Escherichia coli expressing human CYP3A4. First, the metabolic activity of AFB1 by recombinant human CYP3A4 was evaluated. As a result, we confirmed that recombinant human CYP3A4 metabolizes 98% of AFB1. Next, we found that aflatoxin Q1, a metabolite of AFB1 was no longer mutagenic. Furthermore, we revealed that about 50% of the AFB1 metabolic activity can be maintained for 3 months when E. coli expressing human CYP3A4 is freeze-dried in the presence of trehalose. Finally, we found that 80% of AFB1 in A. flavus-contaminated maize was metabolized by E. coli expressing human CYP3A4 in the presence of surfactant triton X-405 at a final concentration of 10% (v/v). From these results, we conclude that AFB1 in A. flavus-contaminated maize can be detoxified under normal temperature and pressure by using E. coli expressing human CYP3A4.

• Journal of Korean Biological Nursing Science
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• v.2 no.1
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• pp.49-63
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• 2000

Aflatoxin $B_1(AFB_1)$ is a potent hepatotoxic and hepatocarcinogenic mycotoxin in human beings. It is accumulated in animal tissues and injured cell through variable metabolic pathway. This study was conducted to determine the effect of antioxidant vitamins on liver function enzymes and hepatic damage of $AFB_1$ treated mice. The 6 weeks old male ICR mice were randomly separated 6 groups, vehicle solvent or vitamin C(10 mg/kg/day) and vitamin E(63.8 mg/kg/day) were administered by intraperitoneal(i.p.) injection and 1 hr later, vehicle solution(DMSO) or $AFB_1$(0.4 mg/kg) were injected. The results obtained as follow ; The levels of liver function enzymes such as GOT, GPT, LDH, and alkaline phosphatase, in sera of mice were remarkably elevated by treatment with $AFB_1$ only. However, those enzymes were significantly alleviated by co-treatment with antioxidant vitamins(p<0.01). Especially the levels of LDH and ALK phosphatase were similar to those of control groups(p<0.01). The transmission electron microscopy(TEM) image of intracellular microrganelles on the liver cell of mice was also degenerated extremely by treatment with $AFB_1$, but vitamin C and vitamin E gave good effects on cellular deformation. The intracellular microrganelles such as mitochondria, endoplasmic reticulum, nucleus and nucleic membrane were nearly disappeared the cellular deformation by antioxidant vitamins co-administration. With above results, we could estimated that antioxidant vitamins blocked AFB1 induced hepatic cell damage.