[Proline-dependent wild strains and proline-dependent mutants of the plague microbe].

It is found that the growth of Yersinia pestis wild strains, isolated from Citellus musicus Menetrié in the Central Caucasus, depends on the presence of proline in the medium. Proline can not be substituted by glutamic acid, other amino acids or vitamins. 28 proline-requiring mutants were selected from Y. pestis marmot strain 20b. Three groups of proline-requiring Y. pestis mutants are established, similar to those of Escherichia coli. The requirement of proline does not affect the virulency, pigment formation and calcium dependence.