A motor driven inoculator is provided wherein a plurality of bacteriological transfer loops are mounted on a common head and are activated in response to the positioning of a tray of inoculum to cause the head to be lowered and then raised so that the loops pick up a sample of inoculum. The subsequent positioning of an antibiotic or antimicrobic microtube plate, etc. causes the head to be lowered and raised a second time so that the loops are lowered into the plate to place samples of inoculum in each of a plurality of wells in the plate by dispersion. The removal of the antibiotic plate initiates a sterilizing cycle wherein the head is lowered and raised a third time whereby the loops are heated to a very high temperature by passing electrical current therethrough to volatilize all material thereon and then they are subsequently air cooled prior to the beginning of the next cycle. In an alternative embodiment the inoculum on the loops may be dispersed by percussion.The inoculum tray includes a plurality of grooves and ridges so that a minimal amount of inoculum is necessary for use in placing samples on the loops by dipping.