Alkylbenzyldimethylammonium Salts as Inhibitors for the Ice Nucleating Activity of Erwinia ananas

Abstract

A variety of chemical compounds were examined as to their abilities to inhibit the ice nucleating activity of Erwinia ananas IN-10 cells and their outer membrane fraction. The nucleating activity of the outer membrane fraction was inhibited by many surface-active species among the compounds examined, whereas that of cells was inhibited only by amines and ammonium salts having amphiphilic structures. Ammonium salts with both an n-alkyl group having a carbon number of more than 8 and a benzyl group were particularly effective in inhibiting the nucleating activity of the bacterial cells. The inhibitory ability of one of the amphiphilic ammonium salts was greater at 15°C than at 4°C. When a tea plant was sprayed with one of the effective ammonium salts prior to being kept at – 3°C overnight, it was possible to protect the plant from freeze-injury at the minimal concentration of 250 ppm.