Influence of culture conditions and virulence plasmids on expression of immunoglobulin-binding proteins of Yersinia pseudotuberculosis.

The influence of culture conditions and plasmids on immunoglobulin (Ig)-binding activity of two isogenic strains of Yersinia pseudotuberculosis (plasmid-free strain 48⁻82⁻ and strain 48⁺82⁺ bearing plasmids pYV48 and pVM82) was studied. The highest activity was observed in the bacteria grown on glucose-containing liquid medium in the stationary growth phase. The Ig-binding activity of the bacteria cultured on the liquid medium at pH 6.0 was about 1.5-fold higher than that of the bacteria grown at pH 7.2. Expression of the Ig-binding proteins (IBPs) was most influenced by temperature of cultivation. The IBP biosynthesis was activated in the bacteria grown at 4°C and markedly decreased in those grown at 37°C. The Ig-binding activity of lysates from the bacteria was caused by proteins with molecular weights of 7–20 kD. The activities of the plasmid-free and plasmid-bearing Y. pseudotuberculosis strains (48⁻82⁻ and 48⁺82⁺, respectively) were analyzed, and the plasmids were shown to have no effect on the IBP expression and biosynthesis, which seemed to be determined by chromosomal genes. [ABSTRACT FROM AUTHOR]