Rapid labelling of bacteria with [¹⁴C]palmitic acid and its application in an aggregation assay

Abstract

A rapid and simple procedure for labelling bacterial cells based on binding of [14C]palmitic acid to the bacterial surface is described. The method was found convenient for both Gram‐positive and Gram‐negative bacteria such as staphylococci, streptococci and Salmonella. Some factors affecting the binding of [14C]palmitic acid to the surface of streptococci were examined. Treatment of bacteria with heat, trypsin or β‐galactosidase had no effect on labelling. The binding was relatively independent of ionic strength in the range 0.1–1 M NaCl, but was dependent on pH and presence of detergents. The [14C]palmitic acid labelling method was tested in studies of aggregation of oral streptococci. The aggregation assay was sensitive and very reproducible.