Abstract
Our recent studies of the effect of electrolytes upon the viability of bacteria have indicated the important influence of even slight variations in hydrogen ion concentration upon such phenomena. Working with Bact. coli we find that hydrogen ion concentrations above pH = 6.0 or below pH = 7.0 give a much more rapid death rate than occurs when the pH is maintained within these limits. Our experiments suggest that a very careful control of hydrogen ion concentration is absolutely essential before valid conclusions can be drawn as to the influence of electrolytes, alone or in combination.
Furthermore, it is essential to follow with care the changes which go on in a suspension of living and dead cells as well as to determine the initial conditions which are provided. We find that a bacterial suspension in 5 isotonic NaCl solution quickly reverts to a pH of about 7.2 whether its initial hydrogen ion concentration be above or below this value. A similar change takes place in a balanced solution of 5 isotonic NaCl + isotonic CaCl2 but at a much slower rate as indicated by the table below.
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