ABSTRACT
A screening of 11956 enterobacteria isolates resulted in selection of seven active microcin-producing strains. The microcins were shown to be peptides or their derivatives with a rather broad spectrum of activity, mainly against Gram-negative bacteria. According to cross-immunity criteria, the microcins studied belonged to two of the previously suggested types, B (five strains) and C (two strains). Those of type B could be further classified into two subtypes on the account of differences in the spectrum of antibacterial activity. In five cases out of seven the microcin-producing ability has been attributed to plasmids that the strains harboured. The effect of microcins on sensitive cells was shown to depend on ompR and ompF gene products.
Subject(s)
Bacteriocins/biosynthesis , Escherichia coli/metabolism , Anti-Bacterial Agents/biosynthesis , Anti-Bacterial Agents/classification , Bacteria/drug effects , Bacteriocins/classification , Bacteriocins/genetics , Drug Resistance, Microbial/genetics , Escherichia coli/genetics , Escherichia coli/isolation & purification , Genes, Bacterial , PlasmidsABSTRACT
As a result of screening among 11956 enterobacteria strains isolated from feces of normal children, grown-ups and lambs, seven active microcin-producing strains were obtained. The microcins were shown to be peptides or their derivatives with a low molecular weight (less than 10,000) and a broad spectrum of activity, mainly against gram-negative bacteria. According to cross immunity criteria the microcins studied belonged to two different types. Those of type I could be further classified into two subtypes on the account of difference in the spectrum of antibacterial activity. In 5 cases out of 7 the microcin-producing ability and immunity to microcins have been attributed to plasmids that the strains harboured. The effect of microcins on sensitive cells depended on ompR and ompF gene products.
Subject(s)
Anti-Bacterial Agents/biosynthesis , Bacteriocins/biosynthesis , Enterobacteriaceae/metabolism , Animals , Drug Resistance, Microbial/genetics , Enterobacteriaceae/genetics , Genes, Bacterial , Humans , Plasmids , SheepSubject(s)
Glomerulonephritis/diet therapy , Chronic Disease , Humans , Menu Planning , Seasons , Uremia/diet therapySubject(s)
Diet , Seasons , Humans , Kidney Diseases/diet therapy , Menu Planning , Urologic Diseases/diet therapySubject(s)
Diet , Seasons , Acute Disease , Chronic Disease , Humans , Intestinal Diseases/diet therapy , Menu PlanningSubject(s)
Diet , Seasons , Communicable Diseases/diet therapy , Gastritis/diet therapy , Humans , Menu Planning , Postoperative CareSubject(s)
Diet Therapy/methods , Food Services , Menu Planning , Animals , Dairy Products , Eggs , HumansSubject(s)
Diet Therapy/methods , Menu Planning/methods , Diet Therapy/standards , Food Services , Humans , Menu Planning/standards , USSRABSTRACT
The adhesive properties and colonizing capacity of E. coli strain O83, isolated from feces of healthy humans and marked according to its resistance to rifampicin and nalidixic acid, were studied. In vivo experiments on germ-free rats revealed that these bacteria were capable of colonizing intestinal mucosa; colonization increased from the small to large intestine and E. coli cells were mainly concentrated in the intestinal lumen and in mucin. In vitro studies showed that this nonenteropathogenic E. coli strain possessed pronounced adhesive properties with respect to the colonic cells of germ-free rats; these properties were considerably less pronounced with respect to the enteric cells of the small intestine. The electron microscopic study of E. coli cells revealed the presence of fimbriae and fibrillae on their surface.
