THE DIFFUSION PRODUCTS OF BACTERIAL CELLS AS INFLUENCED BY THE PRESENCE OF VARIOUS ELECTROLYTES

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Abstract
Observations have been made (1) with a culture of Bact. coli which survives in practically undiminished numbers in distilled water or dilute salt solutions throughout a moderate Ph range and (2) on B. cereus, which dies very rapidly in equivalent solutions (not containing organic protective substances), 90% of the cells being non-viable after 1 hr. In addition to whatever direct absorption of H or OH ions occurs, the cells exert a distinct influence on the reaction of the medium, which may be measured by direct chemical tests after removal of cells. The process involves liberation of acidic substances in alkaline or neutral media and of alkaline substances in more acid media, the resulting solution being so balanced that its ultimate acidity approximates the zone of ph (ph 6.2-6.4) most favorable for viability. On prolonged exposure to a somewhat unfavorable aqueous medium, production of NH3 overbalances that of the acidic substances, and in the case of the cells of B. cereus excess of alkali liberated may be very large. The cells appear to be relatively im- permeable to Cl, phosphate, and to Ca ions. The walls permit free passage of CO2 and NH3. The cell wall of B. cereus is more permeable than that of Bact. coli. Death of the cells of B. cereus leaves NH3 production unimpaired. Death of cells caused by heating at 60[degree] for 15 min. or boiling for 30 min. does not increase the diffusion of the electrolytes studied, nor does it alter the liberation of CO2; it almost wholly inhibits production of NH4. Dilute solutions of NaCl tend to increase the cell permeability. A strong solution of NaCl and solutions of CaCl2 of moderate strength decrease the liberation of NH3 and other alkaline substances and increase the amount of acid substances liberated. A strong CaCl2 solution caused, with Bact. coli, a sharp initial rise in titratable alkalinity in 1 series of experiments and in titratable acidity in 5 series of experiments, followed by a fall which may be interpreted as caused by decrease in permeability leading to lysis and liberation of proteins, in turn followed by accumulation of non-reactive films on the protein micellae, or to absorption of the oppositely charged ions. The current assumption of an inherent antagonism between monovalent and bivalent ions may perhaps be unsound, at least so far as bacterial cells are concerned.

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