RESUMEN
Polymerase chain reaction (PCR) was used for detection of pathogenic Clostridium botulinum, Clostridium perfringens, Clostridium difficile, and Escherichia coli. With this aim in view, primers to botulinic toxins types A, B, C1, D, E, F, and G, perfringens enterotoxin, difficile toxin, and types 1 and 2 Shigella-like toxins were chosen and synthesized. Optimal amplification conditions were selected for each pair of primers, with DNA and the respective agent as the reaction mixture matrices. PCR was highly specific and sensitive in all cases. Its sensitivity was 10-100 cells/sample. Among the tested C. botulinum, C. perfringens, C. difficile, and E. coli strains, specific amplification products of expected size were observed only in the strains containing the respective toxin genes. These findings recommend the use of these methods in clinical microbiology. Strains containing type 2 Shigella-like toxin gene were detected among E. coli strains isolated from patients with the hemolytic uremic syndrome, which for the first time indicates that the problem with E. coli epidemic strain O157 is valid for Russia. As a result of our studies, test systems for detection of types A, B, C, D, E, F, and G C. botulinum strains, C. perfringens and C. difficile, and E. coli O157 strains are now available.
Asunto(s)
Toxinas Bacterianas/genética , Clostridium/aislamiento & purificación , Escherichia coli/aislamiento & purificación , Reacción en Cadena de la Polimerasa/métodos , Toxinas Botulínicas/genética , Clostridioides difficile/aislamiento & purificación , Clostridioides difficile/patogenicidad , Clostridium/patogenicidad , Clostridium botulinum/aislamiento & purificación , Clostridium botulinum/patogenicidad , Clostridium perfringens/aislamiento & purificación , Clostridium perfringens/patogenicidad , Cartilla de ADN , ADN Bacteriano/análisis , Escherichia coli/patogenicidad , Infecciones por Escherichia coli/diagnóstico , Amplificación de Genes , Síndrome Hemolítico-Urémico/microbiología , Humanos , Sensibilidad y Especificidad , Toxina Shiga I/genética , Toxina Shiga II/genéticaRESUMEN
Polymerase chain reaction (PCR) for the identification of C.botulinum of type A was developed. As primers, oligonucleotides corresponding to sequences 913 -- 932 and 1852 -- 1871 of the gene of type A botulinic neurotoxin were used. The study revealed that under optimum conditions the positive result of the reaction was registered only when the DNA of C.botulinum strains of type A (11 strains) was used, but not that of C.botulinum strains of other types (11 strains of type B, 5 strains of type C, 2 strains of type D, 6 strains of type E and 1 strain of type G). High sensitivity, specificity and rapidity of PCR open good prospects for its practical use.
Asunto(s)
Clostridium botulinum/genética , Reacción en Cadena de la Polimerasa/métodos , Secuencia de Bases , Toxinas Botulínicas/genética , Cartilla de ADN , ADN Bacteriano/análisis , ADN Bacteriano/genética , Electroforesis en Gel de Agar , Datos de Secuencia Molecular , Sensibilidad y EspecificidadRESUMEN
The possibility of changing the fatty acid composition of lipids in E. coli strain BB 20-14 by the introduction of ready lipid vesicles obtained from other E. coli strains into the growth medium has been established. Using E. coli strain BB 20-14 as an example, the dependence of the viability of bacteria on their fatty acid composition has been demonstrated.
Asunto(s)
Microbiología del Aire , Escherichia coli/fisiología , Medios de Cultivo/metabolismo , Escherichia coli/análisis , Ácidos Grasos/análisis , Glicerofosfatos/metabolismo , Lípidos de la Membrana/análisis , Lípidos de la Membrana/metabolismoRESUMEN
The death of aerosolized bacteria has been shown to occur as the result of irreversible conformation changes in their macromolecules. This process depends on the role of cell dehydration and the amount of hydration water remaining in the cells.
Asunto(s)
Desecación , Escherichia coli/fisiología , Humedad , Aerosoles , Fenómenos Biofísicos , Biofisica , Sustancias Macromoleculares , Conformación Molecular , beta-Galactosidasa/metabolismoRESUMEN
Comparative experiments on auxotrophic E. coli grown in rich nutrient L-broth have demonstrated that the influence of genes psd 2 and gps A 20 responsible for the synthesis of phospholipids in the bacterial membranes on the viability of the cells is unessential. The cultivation of strain BB 20-14 in a minimal E medium with different glycerophosphate admixtures has shown that the decrease of phospholipid content in the cells to one-third of the original level leads to a considerable change in the viability of the cells in the air.
Asunto(s)
Microbiología del Aire , Escherichia coli/genética , Genes Bacterianos , Genes Letales , Aerosoles , Genotipo , Lípidos de la Membrana/genética , Mutación , Fosfolípidos/genética , TemperaturaRESUMEN
The study of the spectrum of the main fractions of proteins contained in the outer membrane of E. coli strains has revealed the relationship between the composition of protein fractions in the outer membrane and the level of the survival of these bacteria in the air. The increased survival capacity of E. coli strain K12 after the transfer of pSA 50 plasmid has been found to correlate with the appearance of 2 molecular fractions in the outer membrane. The positions of these fractions correspond to the molecular weights 70,000 daltons and 80,000 daltons.
Asunto(s)
Microbiología del Aire , Proteínas Bacterianas/análisis , Escherichia coli/análisis , Proteínas de la Membrana/análisis , Electroforesis en Gel de Poliacrilamida , Escherichia coli/genética , Genotipo , PlásmidosRESUMEN
In experiments on an isolated liver of animals ion-exchange chromatography of the concentration of free amino acids in the perfusate has shown that amino acids with branched chains are metabolized by the liver tissue to a less measure than other amino acids. Under high protein diet the liver capacity for metabolizing most amino acids, except valin, leucin and isoleucin is increased. The data obtained are discussed from the standpoint of transformation of amino acids with branched chains.
Asunto(s)
Aminoácidos de Cadena Ramificada/metabolismo , Hígado/metabolismo , Absorción , Adaptación Fisiológica/efectos de los fármacos , Animales , Proteínas en la Dieta/administración & dosificación , Radicales Libres , Técnicas In Vitro , Ratas , Factores de TiempoRESUMEN
Following determination by the method of ion-exchange chromatography of free amino acids in the blood drawn from the portal and liver veins and the abdominal aorta 30 minutes after introduction of a casein suspension to rats it was found that only 50 per cent of amino acids with ramified chain are retained in the liver. Most of the other amino acids, however, become metabolized largely in the liver and it is only their insignificant part that goes into the general circulation. These data may be of use in considering problems related to the peculiarities of metabolism of amino acids with ramified chain.