A Multipoint Inoculator for Plating Bacteria or Yeasts

SUMMARY: A multipoint inoculator has been designed for inoculating agar plates with a maximum of twenty-four strains of bacteria or yeasts simultaneously. In a previous paper (Beech Carr, 1955) describing the effect of inhibitory compounds on bacteria and yeasts it was found necessary to make approxi-mately 15,000 separate inoculations. This was time-consuming, and since each plate had to be opened twenty-four times the chances of aerial contamination were considerable. The same problem arises when determining the utilization of sugars, etc., by yeasts, with the auxanographic plate method. These difficulties may be overcome by the simultaneous inoculation of the plate with the required number of organisms. Earlier references to such methods have been a multiple-point needle (Garrett, 1946) for inoculating an agar plate with plaques of mould colonies and a replica plating method using circles of velveteen (Lederberg Lederberg, 1952). Garrett’s instrument was not ideal for bacteria and yeasts. In the second method each velveteen circle can only be used for approximately five