Nonspecific and cooperative binding of lectins to microorganisms

Binding of lectins to microbial cell walls was investigated by fluorimetric titration and Scatchard plot. Data were correlated with agglutinability. Concanavalin A and lectins of wheat germ, soybean, pea, lentil, and peanut were tested against Escherichia coli. Micrococcus luteus, Lactobacillus plantarum, and Bacillus subtilis. In cases where binding occurred, it was either nonspecific or positively cooperative. Agglutination was observed only in those combinations of lectin and microorganism that showed positive cooperative binding, suggesting a definite relation between binding and agglutination. Lectins binding to the same carbohydrate did not necessarily bind to the same microorganism, confirming the complexity of the lectin-receptor bond.