It is known that bacterial adhesion to tissues plays an important role in microbial infection and that organisms attached to a surface can express a characteristic phenotype. Although Bordetella pertussis, the etiological agent of whooping cough, has adapted itself to colonise the human respiratory tracts, most of the studies of the expression of their virulence factors have been obtained from bacteria cultivated as cell suspension in liquid media. In this work, we show that B. pertussis can grow attached to an abiotic surface and that this attachment stimulates the production of exopolymers (slime) leading to the formation of biofilms. By using Fourier transform infrared spectroscopy (FT‐IR) analysis, we found that these biofilm‐grown cells are chemically different from the cells grown in both, liquid and solid media. Furthermore, we demonstrated that this slime is mainly composed of carbohydrates.
We have previously shown that fungicide Mancozeb causes a 50% decrease in Bradyhizobium sp USDA 3187 growth rate and affects the bacteria-root symbiotic interaction. In order to elucidate the fungicide toxicity mechanism we determined the effects of Mancozeb on cell chemical composition, glutathione (GSH) content (molecule involved in the detoxification process), glutathione S-transferase (GST) activity and on polyamine, exopolysaccharides, capsular polysaccharides and lipopolysaccharides. Mancozeb produced biochemical alterations in membrane composition, polysaccharides and polyamines. In spite of the increment of GSH content and GST activity, they are not enough to prevent the growth diminution.
Objetivos: 1. Completar los estudios bioquímicos realizados en el INTA de Márcos Juárez, Córdoba, a los fines de confirmar que los aislamientos obtenidos por dicho laboratorio de animales con diagnóstico de queratoconjuntivitis, y que fueron los que utilizamos en nuestros estudios, corresponden a M. bovis. 2. Determinar la estabilidad del fenotipo pifiado de M. bovis en pasajes seriados en medio sólido y líquido. 3. Determinar en medios de cultivo sólido, la movilidad por twitching en poblaciones piliadas y no piliadas de M. bovis. 4. Determinar la presencia del gen de la pilina en variantes piliadas y no piliadas de distintos aislamientos locales de M. bovis. 5. Comparar el perfil de plásmidos de variantes pifiadas y no pifiadas de aislamientos locales de M. bovis. Analizar si se producen modificaciones en dichos perfiles durante el crecimiento en medios sólidos y líquidos. 6. Monitorear la actividad hemolítica durante el crecimiento de M. bovis en medios líquidos a fin de establecer la cinética de producción y estabilidad de la misma.
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