THE ISOELECTRIC POINT OF BACTERIAL CELLS

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Abstract
The fundamental definition of the true isoelectric point as applied to colloidal particles was discussed. Estimation methods applied to bacterial cell suspensions were examined from a theoretical point of view. It was concluded that dye adsorption at different pH levels would not give a true value for the isoelectric point. 31 spp. of bacteria were studied by microelectrophoretic methods to determine the pH at which the cells exhibited no electrical charge. Under standardized conditions, with a dilute monovalent buffer, no fundamental differences were detected between the Gram-negative and Gram-positive groups of bacteria with respect to the pH of the isoelectric point. These findings are in agreement with a large number of similar values found by other workers who were primarily interested in other electrophoretic behavior of the bacteria.
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