A comparison of bacterial aggregation induced by saliva, lysozyme, and zinc.

Aggregation of bacteria by zinc and lysozyme was studied and compared with aggregation induced by a high-molecular-weight salivary agglutinin. Each ligand was found to exhibit a unique profile of properties when examined by both a microradiochemical centrifugation assay and a turbidimetric assay. Significant differences in rate of aggregation and bacterial species specificity were noted. Zinc- and lysozyme-mediated aggregations were shown to be calcium independent and to proceed rapidly at 0 degree C, in contrast to the salivary agglutinin. Zinc produced large, asymmetric aggregates, saliva produced intermediate-sized aggregates, and lysozyme produced the smallest aggregates. These size differences are consistent with many of the observed reaction properties.