On the phase reversal of the lipoid-aqueous systems in the bacterial cell wall.

In previous communications, Mellon 1 , 2 has shown that the principle of ion antagonism is applicable to bacteria. Under the conditions of the experiment with strain N.D.—67 the principle operated in a Na: Ca ratio as high as 100 or 150 to 1. This strain, which is quite stable in H₂O and NaCl solutions, is quickly precipitated by CaCl₂ solutions in strengths as dilute as 10^-6 cm. The physico-chemical mechanism suggested was reversal of the aqueous-lipoid system in the wall of the cell whereby CaCl₂ made the lipoid layer the external phase. This theory is in accord with the work of Clowes 3 with the simple oil-water emulsions.

It was determined to test the validity of this conception by the surface tension method. Mudd 4 has shown that the tubercle bacillus when placed at the interface between an aqueous and a lipoid or a lipoid solvent will always be drawn into the latter by virtue of the large amount of wax contained in this organism. It was thought that the occurrence of the same phenomenon would be strong evidence for a reversal of the aqueous-lipoidal relations of our N.D.—67 by CaCl₂.

Accordingly the organisms were placed in CaCl₂, solution in concentrations ranging from 10^-1 to 10^-6 and this solution shaken with organic lipoidal solvents, such as cyclohexanol, amyl alcohol, capryl alcohol and pelargonic acid. In every instance the organisms were found on the organic side of the phase boundary when the latter formed. They did not pass aver to the aqueous side under the time of observation, which was several days.

A series of higher alcohols was used that showed a progressively increased solubility in H₂O as follows: Di-butyl carbinol < than Di-propyl carbinol which is < than Di-ethel carbinol.