Isolation and properties of mutants of Lactobacillus fermenti resistant to Amprolium.

A series of mutant strains of Lactobacillus fermenti resistant to the growth inhibitory properties of amprolium were isolated by serial transfers of the original strain in media which contained increasing concentrations of amprolium. Using three different resistance levels of strains (resistant strain A, B and C), the mechanism of amprolium resistance was investigated. Through the present studies, the relation between the degree of resistance and the thiamine uptake potential was elucidated.