A soil bacterium, designated strain no. 27, was found to produce aflatoxin-production inhibitors. The strain was identified as a species of the genus Stenotrophomonas, and was found to be closely related to Stenotrophomonas rhizophila. Two diketopiperazines, cyclo(L-Ala-L-Pro) and cyclo(L-Val-L-Pro), were isolated from the bacterial culture filtrate as main active components. These compounds inhibited aflatoxin production of Aspergillus parasiticus and Aspergillus flavus in liquid medium at concentrations of several hundred mM without affecting fungal growth. Both inhibitors inhibited production of norsorolinic acid, a biosynthetic intermediate involved in an early step of the aflatoxin biosynthetic pathway, and reduced the mRNA level of aflR, which is a gene encoding a key regulatory protein necessary for the expression of aflatoxin-biosynthetic enzymes. These results indicated that the inhibitors targets are present in early regulatory steps leading to AflR expression. Co-culture of strain no. 27 with aflatoxigenic fungi in liquid medium effectively suppressed aflatoxin production of the fungus without affecting fungal growth. Furthermore, application of the bacterial cells to peanuts in laboratory experiments and at a farmer's warehouse in Thailand by dipping peanuts in the bacterial cell suspension strongly inhibited aflatoxin accumulation. The inhibitory effect was dependent on bacterial cell numbers. These results indicated that strain no. 27 may be a practically effective biocontrol agent for aflatoxin control.

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DOA-Aflatoxin ELISA Test Kit is an in-house (ELISA test) kit produced by Department of Agriculture (DOA) Ministry of Agriculture and Cooperatives. The test kit had been validated for their precision and accuracy for aflatoxin B1 detection in agricultural commodities. However, proficiency testing of analysis using DOA-Aflatoxin ELISA test kit is an essential element of test kit quality assurance. The analysis performance could be compared the analytical results with those from other laboratories with different methods.The test materials of animal feed, pistachio paste, peanut butter slurry, peanut and chilli powder were prepared and sent to our laboratory by FAPAS (Food Analysis Performance Assessment Scheme). The analysis was performed for aflatoxin B1 using DOA-Aflatoxin ELISA test kit. The satisfactory results of Zscore were obtained from the tests. Performance in a FAPAS proficiency testing, therefore is considered satisfactory if a participant's Z-score lies within the range of-2 and +2.

Polyclonal antibodies against fumonisin B 1 (FBi) were produced in the rabbits after immunizing the animal with FmBI-brovine serum albumin. A direct competitive enzyme-link immunosorbent assay (ELISA) was used to characterize the antibodies and for analysis of the toxin in corn samples.The serum against FB 1 was obtained from the rabbit after 5 weeks of immunization. The highest antibody titer was found in the sera of rabbit 10 weeks after immunization with the titer of 1:25,000 The conjugation of FB 1-HRP was achieved by a water soluble carbodiimide (EDPC). The appropriate time of the reaction between FB 1 and FB 1-HRP in competition to bind the antibody at the bottom of the well was 60 minutes.A good correlation was found between FB 1 level in naturally contaminated corn samples analyzed by direct ELISA and the high pressure liquid chromatography (HPLC) method. The correlation coefficient of a linear regression between ELISA and HPLC data was found to be 0.9732.

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