INDUCED COLONIAL VARIATION OF A TOTAL POPULATION AMONG CERTAIN LACTOBACILLI

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Abstract
Strains representing Lactobacillus helveticus, L. acidophilus, L. brevis, and certain unidentified spp., that normally appear as rough colonies when growing on an adequate tomato agar, can be shifted in toto to smooth colonial forms. Sorbitan monooleate can alter the colonial morph. of these strains from 100% rough to 100% smooth colonies. Colonies of the 2 types appear in equal numbers. The size and rate of development of smooth colonies developing in the presence of sorbitan monooleate are greater than those of rough colonies developing in its absence. Since the descr. change is not permanent and can be reversed in either direction at will, these results are attributed to variation of physical and nutritional factors in the medium and apparently no mutations are involved.
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