VITAMIN REQUIREMENTS OF ORAL LACTOBACILLI

¹ The Walter G. Zoller Memorial Dental Clinic and the Department of Bacteriology and Parasitology, University of Chicago, Chicago, Ill.

The vitamin requirement of 26 strains of oral lactobacilli was studied. These cultures were obtained from carious lesions, plaques, and saliva; 11 of them were laboratory stock cultures, the other 15 were recently isolated.

From 4 to 6 vitamins were required by the different cultures for growth in a basal medium of casein digest, glucose, acetate, and salts. Although this growth was slower than in media containing products such as yeast extract, it could be carried through successive transfers in the presence of the needed vitamins.

All of the oral lactobacilli required nicotinic acid, pantothenic acid, and biotin. Many of them required vitamin B₆ (supplied as pyridoxamine), or pteroylglutamic acid, or both. The need for vitamin B₆ and pteroylglutamic acid, when it occurred, was not always an absolute one, some strains developing poorly without one or the other of these compounds. Seventeen of the cultures required riboflavin and not thiamine, while 8 others required thiamine and not riboflavin.

A thiamine requirement was associated with the heterofermentative type of glucose metabolism, a finding in agreement with the previous report of others.

There were no essential differences in vitamin requirement between the older laboratory cultures as a group and the more recently isolated ones.

Purines and pyrimidines when added with the vitamins often accelerated the rate of growth, in some instances quite markedly. A mixture of several purines and pyrimidines produced a greater stimulation of growth than the individual compounds.