Spontaneous Kanamycin-resistant Escherichia coli mutant with altered periplasmic oligopeptide permease protein (OPPA) and impermeability to aminoglycosides

A spontaneous kanamycin-resistant Escherichia coli mutant, showing cross resitance to five other aminoglycosides and absence of the OppA protein was isolated. [3H]- dihydrostreptomycin uptake is reduced in this mutant, implying that the oligopeptide transport system in involved in accumulation of aminoglucosides, although apparently not related with aminoglycoside permeability alteration due to bacterial adaptation to osmotic changes.

Cell envelope components of Yersinia pestis grown in intraperitoneal diffusion chambers

The electrophoretic profiles binding of penicillin binding proteins (PBPs) and outer membrane proteins (OMPs) of Yersinia pestis EV 76 were determined following in vivo growth in diffusion chambers implanted in the peritoneal cavity of mice. In contrast to Y. pestis grown under in vitro conditions which activate the low calcium response (LCR) regulon there was no significant qualitative or quantitative change of the PBP profile of Y. pestis cells during growth in diffusion chambers for up to 72 h following implatation in mice. Three OMPs, with molecular weight of 100, 60 and 58 kDa, were expressed in Y. pestis cells grown for 24 h, but not at 48 h or at 72 h, in diffusion chambers. These results indicate that growth of Y. pestis in intraperitoneal diffusion chambers activates genes which might be relevant to the growth in the mammal host.