Three types of biological methods were compared as detectors of stachybotrys toxin. The seven preparations tested represented “crude” or partially purified toxins produced by different strains of Stachybotrys alternans and toxic fractions obtained by partial purification of the product of one strain. The order of sensitivity of the methods was almost invariably: the mouse fibroblast test most sensitive, the rabbit skin test next, and the brine shrimp (Artemia salina) test last. A conspicuous variation by preparation in relative sensitivity of the mouse fibroblast test and the rabbit skin test was revealed, however. The variation ranged from a sensitivity of the rabbit skin test approximately 2.5 times higher than that in the mouse fibroblast tests to the other limit when the mouse fibroblast test was 80 times more sensitive than the rabbit skin test. The variation is interpreted to provide the first experimental proof of heterogeneity in biological effect based on chemical differences among the compounds constituting “stachybotrys toxin”. The toxic fractions obtained by purification of two crude preparations and identified as toxic by the mouse fibroblast test showed different patterns of distribution of toxicity. The results demonstrate that qualitative differences may exist in the chemical structure of the population of toxic compounds of “stachybotrys toxin” produced by different strains of S. alternans.
Nineteen Stachybotrys alternans strains isolated from animal feeds, fodder or bedding and from grain for human consumption were tested for their toxin‐producing capacity on a mixture of wheat, oats and barley. Ultraviolet light was applied during isolation of the fungi. Nine out of the 19 strains were toxic to white mice in a feeding experiment of two week's duration. Five selected strains were also tested by the rabbit skin test and by the feeding test with guinea pigs. Clinical symptoms and patho‐anatomical pictures are described. The reason why S.alternans has been rarely found in grain is discussed.
Chromatographic analyses and tissue culture toxicity tests were simultaneously carried out with stachybotrys crude toxin. Toxic fractions were localized by tissue culture toxicity tests, and further chemical analyses were concentrated on these parts. By using consecutive partition chromatography on silica gel columns with different solvent systems the crude toxin was resolved into three components which were toxic to mouse primary fibroblast culture. These three toxic stachybotrys components contained some impurities, they were non‐fluorescent and they gave a negative resorcinol test.
Isolation of 73 Stachybotrys alternans strains from various materials, their morphological description and results from toxigenicity tests by a tissue culture method are reported. The isolation method consisted of culturing the material on wet cotton wool and sterile filter paper. Out of the 725 samples of cereal grain, field pea, oat meal, feed and fodder sent for routine mycological investigation 50 strains of S. alternans were isolated. Rather strikingly, approximately every fourth of the samples of field pea seed was found to be contaminated with S. alternans. Among the 129 samples of feed and fodder suspected as a cause of mycotoxicosis in domestic animals, 22 turned out to be contaminated by S. alternans. The toxicity of ether soluble extracts from strains cultivated on wheat‐oats‐barley mixture was tested in mouse primary fibroblast cultures. Together 49 out of the 73 isolated strains were found toxigenic by the test. All 13 strains isolated from field pea samples produced toxin. No relation between morphological characteristics and toxicity was revealed.
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