STUDIES ON THE SELECTIVE MEDIUM FOR THE COLI-FORM GROUP (1)

Abstract

A study was made to prepare as medium which will permit a selective growth of the coli-form group of bacteria but supress, as effectively as possible, the growth of other bacteria.
In as much as the coli-form group has a property very similar to that of Pseudomonas or Proteus, the bacteriostatic power of drugs alone cannot be used when proteins or peptones are the fundamental nourishment.
Consequently, lactose instead of glucose was used in Stephenson-Whetham's synthetic medium. Some Crystal violet and Hexylresorcinol were added as bacteriostatic drugs. The addition of these two drugs was adopted after considering the result of some experiments as well as many literatures up to this time. As a result of repeated experiments, a fairly satisfactory medium was obtained when 0.1mg of crystal violet per L and 8mg of hexylresorcinol per L of medium was used.
A more detailed experiment made in order to determine the optimum concentration of drugs will be reported in the next paper.