A COMPARATIVE STUDY OF ORAL LACTOBACILLI ISOLATED ON TWO DIFFERENT MEDIA FROM THE HUNT-HOPPERT RATS

¹ Departments of Zoology, Microbiology, and Public Health, Michigan State University, East Lansing, Mich.

A comparative study has been made on 100 strains of rat oral lactobacilli isolated from lactobacillus-selection medium and an equal number of strains isolated from tomato juice agar. In contrast with lactobacilli isolated from tomato juice agar, most of the strains from lactobacillus-selection medium appeared to be of 1 type, generally did not ferment dextrin or salicin, and only 1 strain fermented mannitol. These organisms rarely curdled litmus milk and did not reduce the pH of a dextrose broth medium as much as strains from tomato juice agar. These strains grew well in a synthetic medium containing Tween 80 whereas the growth of organisms isolated from tomato juice agar was sparse in the same medium. The majority of tomato juice agar lactobacilli did not grow on lactobacillus-selection medium which indicates that a medium designed to select a group of organisms may be inhibitory to certain strains.