HERNÁ N DE Z. 1997. Six mice were immunized intraperitoneally (i.p.) with a chemically synthesized 9-mer fragment (PH1) designed from the N-terminal part of the bacteriocin pediocin PA-1 and conjugated to keyhole limpet haemocyanin (KLH). After three doses of the immunogen had been administered, serum-specific antibodies were detected by a competitive direct ELISA. Myeloma cells were injected i.p. into mice in order to obtain ascites polyclonal antibodies. Although four mice developed ascites, only mouse 2 had detectable specific antibodies in the ascites fluid. The serum and ascites antibodies were specific for PH1 but they did not recognize the whole pediocin PA-1 molecule. This is the first attempt to generate antibodies against bacteriocins with a chemically synthesized oligopeptide as immunogen. This approach still remains attractive for detection, quantification, mode of action studies and purification of bacteriocins, especially those for which the purification process is difficult or inefficient at present.

To assess the potential for mycotoxin contamination of the human food supply following the 1988 U.S. drought, 92 grain food samples were purchased from retail outlets in the summer of 1989 and surveyed for aflatoxin Bl, zearalenone, and deoxynivalenol (DON [vomitoxin]) by monoclonal antibody-based competitive enzyme-linked immunosorbent assay (ELISA). Only one sample (buckwheat flour) was found to contain aflatoxin B1 (12 ng/g), whereas zearalenone was found in 26% of the samples at a mean concentration of 19 ng/g. In contrast, the DON ELISA was positive in 50% of the samples at a detection level of 1.0 ,ug/g. Between 63 and 88% of corn cereals, wheat flour/muffin mixes, rice cereals, and corn meal/muffin mixes yielded positive results for DON, whereas 25 to 50% of oat cereals, wheat-and oat-based cookies/crackers, corn chips, popcorn, and mixed-grain cereals were positive for DON. The mean DON content of the positive samples was 4.0 ,ug/g, and the minimum and maximum levels were 1.2 and 19 ,ug/g, respectively. When positive ELISA samples were also analyzed by high-performance liquid chromatography, a strong correlation between the two methods was found. The presence of DON in the two highest samples, corn meal and mixed-grain cereal, which contained 19 and 16 ,ug/g, respectively, was quantitatively confirmed by gas chromatography-mass spectrometry. The results indicated that DON was present in 1989 retail food products at concentrations that exceeded those found in previous market surveys and that have been experimentally associated with impaired animal health.

The lantibiotic nisin A was purified to homogeneity by a single-step immunoaffinity chromatography method. An immunoadsorption matrix was developed by direct binding of anti-nisin A monoclonal antibodies to Nhydroxysuccinimide-activated Sepharose. The purification procedure was rapid and reproducible and rendered much higher final yields of nisin than any other described method.

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A sandwich ELISA (enzyme-linked immunosorbent assay) was developed for the detection of defined amounts of bovine milk (1–30%) in ovine milk. Polyclonal antibodies were raised in rabbits against bovine whey proteins (BWP). Resultant antibodies were affinity purified by immunoadsorption of the crude antiserum onto columns containing immobilized ovine, caprine, and BWP, followed by elution of the bovine milk specific antibodies (anti-BWP) from the column containing the bovine proteins. The specific anti-BWP antibodies bound to the wells of a microtiter plate were used to capture the BWP from milk mixtures. Further immunorecognition of the captured proteins was attained with the same specific antibodies conjugated to biotin. ExtrAvidin-peroxidase was used to detect the biotinylated antibodies bound to their specific antigens. Subsequent enzymic conversion of substrate gave clear optical density differences when assaying mixtures containing variable amounts of bovine milk.