Studies on salt action. II. The effect of transfer from stronger to weaker salt solutions upon the viability of bacteria in water

Abstract

In continuation of work previously reported, upon the viability of B. communis in salt solutions of various kinds, 2 we have studied the effect of transfer from salt solutions to weaker salt solutions, in order to see if phenomena could be detected analogous to those observed by Loeb 3 and others in the study of the influence of salt solutions upon the swelling of animal membranes and powdered colloids.

B. communis was grown on nutrient agar slants at 37° C. for 16-18 hours. The growth was washed off in pure redistilled water, shaken for five minutes to break up clumps and added in 1 c.c. portions to the electrolyte solutions in which the preliminary treatment was to be accomplished (“primary” solutions), which had been previously warmed to 37° C. The solutions were then shaken for one minute to give a homogeneous suspension, 1 c.c. was withdrawn and agar plates poured. The bottles containing the suspensions were then replaced in the incubator at 37° C. and kept there for 30 minutes (in one case 60 minutes). At the end of this interval plates were again made, 1 c.c. withdrawn and transferred to another bottle containing 99 c.c. of water or salt solution (“secondary” solution). These secondary solution bottles were then returned to the incubator and kept there throughout the remainder of the experiment. The number of organisms surviving was determined at stated intervals. The counts were made on standard agar after 24 hours incubation at 37° C. and kept there for 30 minutes (in one case 60 minutes). At the end of this interval plates were again made, I C.C. withdrawn and transferred to another bottle containing 99 C.C. of water or salt solution (“I secondary” solution).