Identification of aggregation substances of Enterococcus faecalis cells after induction by sex pheromones. An immunological and ultrastructural investigation.

The sex pheromone system of Enterococcus faecalis is responsible for the clumping response of a plasmid carrying donor strain with a corresponding plasmid free recipient strain due to the production of sex pheromones by the recipient strain. The clumping response is mediated by a surface material (called aggregation substance) which is synthesized upon addition of sex pheromones to the cultures. Here we show that after induction a dense layer of "hairlike" structures is formed on the cell wall of the bacteria. These hairlike structures are responsible for the cell-cell contact which leads to the aggregation of cells. Formation of these structures was specific, only occurring after the addition of homologous sex pheromone.