A Bacteriological Conductivity Culture Cell and Some of Its Applications

Impedance microbiology—a rapid change for microbiologists

“…It was first mentioned at a meeting of the British Medical Association at Edinburgh in July 1898 where Stewart presented a paper later to be published in The Journal of Experimenta 1 Medicine entitled 'The changes produced by the growth of bacteria in the molecular concentration and electrical conductivity of culture media' (Stewart 1899). The electrical response curves presented followed the putrefaction of blood and serum and were very similar to those obtained from currently available impedance systems, the significant difference being that today impedance can be considered as a rapid microbiological method whereas Stewart was measuring changes in impedance over periods in excess of 30 d. Further work followed on from Stewart's initial findings (Oker-Blom 1912 ;Parsons and Sturges 1926;Parsons et al 1929;Allison et al 1938;McPhillips and Snow 1958). However, it was not until the mid seventies that the technique began to receive the attention it merited.…”

Experimental Studies of Natural Purification in Polluted Waters: VII. The Selection of a Dilution Water for Bacteriological Examinations

“…Butterfield (1929) and Parsons et al (1929) have shown that certain bacteria in dilute mediums grow best, and without lag, at a pH of about 7.0. Undoubtedly with mixed cultures of bacteria, as the hydrogen ion concentration changes from the zone of pH 7.0, where optimum growth is obtained, to the zone of pH 9.0, where bactericidal effects are observed, varying conditions of growth will be encountered.…”

The Selection of a Dilution Water for Bacteriological Examinations

“…At this point in the consideration of dilution water effects, distinction must be made between the death of the bacterial cell (as evidenced by an inability to grow w-hen transferred from a dilution water to a suitable culture medium), and the ability to grow without lag in a medium diluted with such a water. Butterfield (1929) andParsons et al (1929) have shown that certain bacteria in dilute media grows best, and without lag, at a pH of about 7.0. Undoubtedly with mixed cultures of bacteria, as the hydrogen ion concentration changes from the zone of pH 7.0, where optimum growth is obtained, to the zone of pH 9.0, where bactericidal effects are observed, -arying conditions of growth will be encountered.…”