A Quantitative Study of Environmental Factors Involved in Survival and Death of Bacteria in the Desiccated State

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Abstract
Death rates were calculated from data obtained by agar-plate counts on dried bacteria in several environments at stated intervals. The Flosdorf-Mudd "lyophile" apparatus was used to desiccate the organisms. Under the test conditions, the death rates of Streptococcus hemolyticus strain C203 and Escherichia coli communior were found to proceed logarithmically. In all menstruums the streptococci were viable for longer periods in the desiccated state than in their fluid counterparts. The reverse was true for E. coli. Death rates were highest for both organisms when dried in dist. water. Significant decreases in the death rates occurred when the organisms were dried in a menstruum containing crystalline compounds of high solubility and which the organism can dissimilate in normal fluid media. This decrease in death rate was less marked in dissimilable crystalline compounds of low solubility, than with non-dissimilable compds. of high or low solubility. When streptococci were dried in the presence of colloidal substances, the death rates decreased with increases in the hydrophilic property of the colloid. In the presence of mixtures of dissimilable crystalline compounds and hydrophilic colloids, the death rates of the dried streptococci and colon bacilli were further decreased below the values obtained with either group of compounds alone.

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