A Simple, Quantitative Method for Measuring Chemotaxis and Motility in Bacteria

Abstract

A method which can be used to measure positive and negative chemotaxis in bacteria quickly and accurately is described. The method uses a Coulter counter to measure the percentage of a suspension of motile bacteria passing through a polycarbonate membrane in a given time, into a cell-free buffer, under a chemotactic influence. This method can also be adapted for measuring the percentage of motile bacteria in a culture. This is achieved by comparing the number of bacteria passing through the membrane in a given time with standards of known percentage motility. Strains of Escherichia coli, Streptococcus faecalis, Proteus mirabilis and Bacillus megaterium were used.