• Journal of Food Hygiene and Safety
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• v.12 no.4
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• pp.281-287
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• 1997

We have reported a sensitive, specific and simple direct competitive ELISA method to detect aflatoxin in agricultural commodities. We evaluated the ELISA for practical use to detect aflatoxins contaminated in the domestic and foreign agricultural commodities. The detection limits of the direct ELISA for residual aflatoxins in rice, pine nuts, corns, almonds, bean nuts, and pistachio were 10 ppb and in peanuts and cashew nuts were 20 ppb, which were elucidated from the standard curves of ELISA for aflatoxin fortified into the agricultural commodities. Residue studies of naturally contaminated aflatoxins in the agricultural commodities were also carried out by using direct ELISA. As the results of the studies, it was revealed that there were no residues of aflatoxins in 20 rice samples produced in south Korea, 20 pine nut samples in south Korea (9 samples), USA (1 sample) and China (10 samples), each of 20 almond, pistachio and bean nut samples in USA. However, aflatoxin residues were detected in corn samples imported from north Korea (350∼585 ppb in 2 of 3 samples), from USA (109*326 ppb in 6 of 6 samples) and domestic corns (61-326 ppb in 7 of 17 samples). The toxins were contaminated in corn imported from USA for popcorn (17∼20 ppb, in 3 of 10 samples) whereas no residues were detected in corn from south Korea and China. In case of cashew nuts imported from India, 11.4∼23.1 ppb of aflatoxins were detected in 4 from 20 samples. Most of the contaminated foods were harvested before 1995. Thus, hygienic managements of the foods should be required during storage and circulation at market.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.99-102
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• 2003

The different methods such as HPLC, indirect- and direct-ELISA were employed for the analysis of microtoxins and the results of each method were compared in terms of the detection limit and accurary. Three toxins, microcystin-RR, -LR and -YR were clearly separated by HPLC using 0.05 M methanol and phosphate buffer used as a solvent system. The calibration curves for the toxins were linear in the range of 5 ng to 50 ng. The standard curves for the immunoassay of microcystin obtained by direct and indirect ELISA are compared. The linear responses of inhibitions of binding by microcystin in the direct and indirect competitive ELISA were in the range of 10 ng to 1000 ng and 50 pg to 160 pg, respectively. Distribution of microtoxins at 11 sites in the Nakdong river and several lakes in Korea was also studied. The most dominant microcystin variant in the test sites was found to be microcystin-RR.

• Reproductive and Developmental Biology
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• v.34 no.3
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• pp.161-167
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• 2010

Early diagnoses of pregnancy for animal such as swine and bovine is extremely important to increase income of a farmhouse and for the management of farm. For the development of immunoasaay system of pregnancy in swine, we report a competitive heterologous enzyme linked immunosorbent assay (ELISA) for the direct measurement of oestrone sulfate (E1S) in diluted urine using anti-E1G (glucuronide) monoclonal antibody which cross react with ElS. The principle of assay was based on the typical solid-phase competitive ELISA methods using E1G-HRP (horseradish peroxidase) as a tracer and E1S for standard. The method had a reasonable sensitivity for the detection of E1S with 0.15 ng/ml as a detection limit. The intra-assay and inter-assay precisions were raging coefficient of from 8.50~9.67% and 8.50~9.87%, respectively, which were quite acceptable. In a field trial with a group 37 sows (18 non-pregnancy and 19 pregnancy sows) after day 29~30 post service, the concentration of E1S were determined to be below 30 ng/ml in all non-pregnancy group and over 48 ng/ml in pregnancy group except one sample. The method described here, heterologous ELISA for the measurement of E1S in urine is good enough for monitoring the early pregnancy test of swine.

• Journal of Microbiology and Biotechnology
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• v.33 no.2
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• pp.228-234
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• 2023

In this study, the performance of a gold biosensor combined with light microscope imaging system (GB-LMIS) was comparatively evaluated against enzyme-linked immunosorbent assay (ELISA) for detecting Salmonella under simulated chilling condition. The optimum concentration of antiSalmonella polyclonal antibodies (pAbs) was determined to be 12.5 and 100 ㎍/ml for ELISA and GBLMIS, respectively. GB-LMIS exhibited a sufficient and competitive specificity toward three tested Salmonella among only. To mimic a real-world situation, chicken was inoculated with Salmonella cocktail and stored under chilling condition for 48 h. The overall growth of Salmonella under chilling condition was significantly lower than that under non-exposure to the chilling condition (p < 0.05). No significant differences in bacterial growth were observed between brain heart infusion and brilliant green broth during the enrichment period (p > 0.05). Finally, both GB-LMIS and ELISA were employed to detect Salmonella at every 2-h interval. GB-LMIS detected Salmonella with a competitive specificity by the direct observation of bacteria on the sensor using a charge-coupled device camera within a detection time of ~2.5 h. GB-LMIS is a feasible, novel, and rapid method for detecting Salmonella in poultry facilities.

• Food Science and Biotechnology
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• v.15 no.6
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• pp.990-992
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• 2006

In a previous study, we obtained polyclonal antibodies against the organophosphorus insecticide fenitrothion and developed an enzyme-linked immunosorbent assay (ELISA) for this pesticide. Using these antibodies and an enzyme tracer, a direct competitive ELISA method specific for fenitrothion using a dipstick format was developed. Dipstick ELISA using antibodies to fenitrothion immobilized on an Immunodyne membrane allowed the quick visual detection of fenitrothion at concentrations above $10\;{\mu}g/L$. The $IC_{50}$ value of dipstick ELISA using reflectance detection was $27\;{\mu}g/L$ with a detection limit of $2\;{\mu}g/L$. The recovery of fenitrothion from spiked lettuce and rice samples using the dipstick ELISA ranged from 87-107%.

• Microbiology and Biotechnology Letters
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• v.25 no.4
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• pp.414-419
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• 1997

In order to develop an enzyme-linked immunosorbent assay (ELISA) for deoxynivalenol (DON) in com, we produced a specific monocl- onal antibody and established ELISA conditions. After the spleen cells from mice immunized with DON-bovine serum albumin conjugate were fused with S$_{p}$2/0 myeloma cells, a hybridoma cell 3G7 producing anti-DON antibody was screened by ELISA. From the standard curve of competitive direct ELISA (cdELISA) using 3G7 monoclonal antibody and DON-HRP conjugate, the detection range of DON showed 3-3,000 ng/ml (ppb). The monoclonal antibody showed some cross-reactivities against DON analogues such as 15 acetyl-DON (110%), nivalenol (5.0%), 3 acetyl-DON (1.7%), fusarenon-x (0.72%), and T-2 (0.59%). When the cdELISA was applied to the spiked coms after extracting with 60% methanol and diluting 5- fold with washing buffer, the assay recoveries of DON were 313, 163, 106, and 88.9% (av., 168%) in the levels of 200, 600, 2,000, and 6,000ng/g, respectively. For the quantitation of DON in coms, 30 samples kept under two different storage conditions of cold and room temperature were assayed by cdELISA. The mean detection concentrations were 595 (detection range, 0-2,750) and 2,448 (detection range, 0-4,500) ppb, respectively.

• Korean Journal of Food Science and Technology
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• v.35 no.2
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• pp.291-296
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• 2003

Effects of Bacillus subtilis and Rhizopus oryzae on chitooligosaccharides (COS) content of doenjang (soybean paste) and kanjang (soy sauce) were investigated using kojis made with the two strains. Competitive direct enzyme-linked immunosorbent assay (cdELISA) system using anti-COS mixture (COSM) antibody was applied for COS detection ranging from 0.001 to $1{\mu}g/mL$, and the recoveries of COSM spiked to doenjang and kanjang were 102 and 115%, respectively. Doenjang and kanjang products made with a mixture of B. subtilis and R. oryzae kojis showed COS contents of 171 and $29{\mu}g/mL$, respectively, during two-month aging period, much higher than those of Japanese and Korean commercial ones.

• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.686-692
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• 2004

To develop the enzyme-linked immunosorbent assay (ELISA) for the analysis of N-acetylehitooligosaccharides (NACOS) and chitooligosaccharides (COS), specific antibodies (Abs) were produced, and their properties were compared. N-acetylehitohexaose (NACOS6), chitohexaose (COS6), and COS mixture (COSM) conjugated to bovine serum albumin (BSA) were used to immunize rabbits. By the use of specific Abs and NACOS6-horseradish peroxidase (HRP), COS6-HRP, and COSM-HRP conjugates, competitive direct ELISA (cdELISA) was developed. The detection limits of NACOS6 by the anti-NACOS6 Ab and COS6 by the anti-COS6 and the anti-COSM Abs in the cdELISAs were about 0.2, 2, ana 2 ng/ml (ppb), respectively. In the cdELISA, the anti-NACOS6 Ab was found to recognize NACOS3-NACOS6, but not N-acetyl-D-glucosamine (GlcNAc), NACOS2, and COSs; the anti-COS6 Ab recognized COS2-COS6 and COSM, but not glucosamine (GlcN) and NACOSs. The recognition pattern of the anti-COSM Ab was almost the same as that of the anti- COS6 Ab, except that the former recognized COS2 and COS3 slightly better than the latter.

• Microbiology and Biotechnology Letters
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• v.24 no.5
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• pp.630-635
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• 1996

For a survey of the occurrence of aflatoxin M$_{1}$ (AFM$_{1}$) in domestic cow's milk, we developed an enzyme-linked immunosorbent assay (ELISA) system, and quantitated the toxin in cow's milk. In order to produce specific antibodies AFM, conjugated to bovine serum albumin (AFM$_{1}$-BSA) and Freund's adjuvant were immunized subcutaneously to rabbits. By use of the antiserum showing the highest titer and AFB$_{1}$-HRP conjugate, we established a competitive direct ELISA (cdELISA) for AFM$_{1}$, whose detection limit was 0.003 ppb. The cross-reactivities of the antiserum against aflatoxin M$_{1}$ M$_{2}$, B$_{1}$, B$_{2}$, G$_{1}$, G$_{2}$, B$_{2a}$, and G$_{2a}$, were 100, 29.9, 25.0, 2.7, 13.0, 0.65, 0, and 0%, respectively. When the cdELISA was applied to the cow's milk spiked with AFM$_{1}$ and followed by cleanup with C$_{18}$ cartridge, the mean recovery of the assay was 104% (mean of CV, 6.4%) in the final concentration of 0.01-1 ppb (10-1, 000 ppt). When cow's milk samples gathered from markets and farms were assayed by the cdELISA, the mean concentration and SD of AFM$_{1}$ was 80.4 $\pm$ 55.0 ppt (n=64; range, 5.6-280 ppt).

• Journal of Food Hygiene and Safety
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• v.13 no.2
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• pp.129-134
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• 1998

To develop an enzyme-linked immunosorbent assay (ELISA) for nivalenol (NIV), we produced polyclonal antibodies against tetraacetyl nivalenol (Ac4-NIV) and established ELISA conditions. Ac4-NIV-hemisuccinate conjugated to bovine serum albumin (Ac4-NIV-HS-BSA) was immunized with Freund's adjuvants into rabbits subcutaneously several times. By use of the antiserum showing the highest titer and Ac4-NIV-HS-HRP conjugate, we established competitive direct ELISA (cdELISA). Standard curve of cdELISA showed that the detection range of Ac4-NIV was about 10~5,000 ng/ml (ppb). The cross-reactivities of the polyclonal antibody towards Ac4-NIV and acetyl T-2 were 100 and 70% respectively, and those towards NIV, deoxynivalenol, 3-acetyl deoxynivalenol, 15-acetyl deoxynivalenol, triacetyl deoxynivalenol, fusarenonX, and T-2 were less than 0.1%. When cdELISA was applied to NIV-spiked corns followed by extraction with 70% acetonitrile and acetylation with acetic anhydride in pyridine, the recovery rates of the Ac4-NIV were 108, 143, and 70% (average, 107%) in the levels of 100, 300, and 1,000 ng/g (ppb), respectively.