[Obtaining Shigella flexneri 2a mutants defective in utilization of certain carbon sources, their genetic and biological characteristics].

Various methods, including selection by resistance to the antibiotic mecillinam have been used to obtain Sh. flexneri mutants capable of utilizing mannitol and mannose as the sources of carbon. The mutation which determines this phenotype is localized in str-spc area and cotransduced with str A gene (28-33%). The appearance of this mutation in the initial Sh. flexneri strain 516 led to a decrease in the virulence of this strain for guinea-pigs. The restoration of its properties and the partial restoration of its virulence could be detected in Mal+ hybrids obtained by crossing with E. coli strain K12- the product of this gene may participate in the regulation of the synthesis of some pathogenicity factor.