A test battery of bacterial toxicity assays and comparison with LD50 values

The toxicity of some mycotoxins, lactones and dicarboxylic anhydrides, insecticides, herbicides, and fungicides can be detected by means of bacterial assays. In addition, the order of magnitude of the toxicity can also be evaluated. Fifty-eight chemicals as well as extracts of peanuts, apple juices, and grains have been investigated in a test battery of three different kinds of assays. In cup plate diffusion assays a minimal amount of approximately 0. 1 mg/mL of mycotoxin may be detected by means of growth inhibition assays with Bacillus thuringiensis on one hand, and pigment synthesis inhibition assays with mutants of Serratia marcescens on the other hand. Swarming inhibition assays with the motile strains Azospirillum brasilense and Proteus mirabilis show the same sensitivity. Comparisons of our test battery with other bioassays, as well as with mammalian toxicity tests (LD50 values), reveal correlations between these kinds of assays in regard to the test substances.