Influence of Deuterium Oxide on Growth and Morphology of Lactobacilli

Abstract

The biological interest in deuterium oxide or heavy water cannot be overlooked because all living cells require water for growth. Barnes reported that Spirogyra showed some unusual and interesting effects when grown in low concentrations of deuterium oxide and that these concentrations had a stimulating effect on the growth of Euglena. Harvey and Taylor recorded that when luminous bacteria were incubated in tubes containing mixtures of heavy water and ordinary water, the amount of oxygen used by the bacteria was in proportion to the percentage of heavy water in the mixture. Also the luminescence of the bacteria was diminished when exposed to low concentrations of heavy water. Richards observed the growth of Saccharomyces cerevisió in weak concentrations of deuterium oxide which he claimed accelerated growth and development, as opposed to its lethal effect in higher concentrations. In order to obtain data on the reaction of other microbiologic forms, we conducted experiments on the growth and morphology of 8 strains of lactobacilli exposed to various concentrations of this water-compound. We are obligated to Professor H. V. Moyer of the Department of Chemistry for the deuterium oxide. The heavy water was mixed with Difco dehydrated whey broth so that the broth contained concentrations of 0.13, 0.7, and 5.0% deuterium oxide. The control broth was prepared with distilled water which was devoid of all deuterium oxide. The various lots of broth, in 10 cc. portions, were sterilized in sealed glass tubes at 15 pounds pressure for 20 minutes. In studying the effect of deuterium oxide, 1 cultures each of L. czcidoplzilus and L. bulgaricus were used. Each culture n-as inoculated into the various lots of esperimental medium, using 0.1 cc. of an actively groving broth culture for each tube. The cultures were incubated at 37C. −\t 12-hour intervals for a 60-hour period, 1 CC. was withdrawn from each tulx and pour plates were prepared with tomato-juice agar, using dilutions of 1:1000, 1:10:000 and 1:100,000 of the cultures.