Bacterias contaminantes en la fase de establecimiento in vitro del guayabo

The guava tree (Psidium guajava L.) is an specie which has demonstrated to be recalcitrant to micropropagation techniques by organogenesis due to microbial contamination and tissue blackening problems. The current work followed as objective: to evaluate the incidence and effect of the bacterial contamination of the guava in vitro establishment as well as to isolate and identify the main contaminants. The work was carried out with 34 nodal segments of guava tree which did not succeed the in vitro establishment. Twenty-eight out of them presented microbial contamination visible on the culture medium, around the base of the explants and sometimes colonizing the same ones. The cultural characters of the contaminants microorganisms in the culture medium for the in vitro establishment were described, isolated and purified. Traditional staining, physiological and biochemical tests were realized for the identification. The obtained results indicated that the microbial contamination and the fenolization limited the in vitro establishment of guava. It was determined that the 76.47% of the samples analyzed presented bacterial contamination, the 5.88% by yeasts and the 17.47% did not presented detectable contaminants. The most frequent contaminants belonged to the Pseudomonadaceae and Enterobacteriaceae families. The injurious effect of the contaminants on the explants of guava were observed and a total necrosis of the same ones was detected.Key words: bacterial contamination, Enterobacteriaceae in vitro propagation, Pseudomonadaceae, Psidium guajavaEl guayabo (Psidium guajava L.) ha demostrado ser una especie recalcitrante a técnicas de micropropagación vía organogénesis, debido a problemas de contaminación microbiana y ennegrecimiento de los tejidos. El presente trabajo persiguió como objetivos: evaluar la incidencia y el efecto de la contaminación bacteriana en el establecimiento in vitro del Guayabo así como aislar e identificar los principales contaminantes. Se trabajó con un total de 34 segmentos nodales de guayabo que no lograron establecerse in vitro. De ellos, 28 presentaban contaminación microbiana visible sobre el medio de cultivo, alrededor de la base de los explantes y en ocasiones colonizando los mismos. Se describieron los caracteres culturales de los microorganismos contaminantes en el medio de cultivo para el establecimiento in vitro, se aislaron y purificaron. Para la identificación se realizaron pruebas tintoriales, fisiológicas y bioquímicas tradicionales. Los resultados obtenidos indicaron que la contaminación microbiana y la fenolización limitaron el establecimiento in vitro del Guayabo. Se determinó que el 76.47% de las muestras analizadas presentaban contaminación bacteriana, el 5.88% por levaduras y el 17.64% no presentaban contaminantes detectables. Los contaminantes más frecuentes pertenecieron a las familias Pseudomonadaceae y Enterobacteriaceae. Se observó el efecto nocivo de los contaminantes sobre los explantes de guayabo detectándose necrosis total de los mismos.Palabras clave: contaminación bacteriana, Enterobacteriaceae, propagación in vitro, Pseudomonadaceae,Psidium guajav

Contaminant bacterium in the phase of in vitro establishment of guava

The guava tree (Psidium guajava L.) is an specie which has demonstrated to be recalcitrant to micropropagation techniques by organogenesis due to microbial contamination and tissue blackening problems. The current work followed as objective: to evaluate the incidence and effect of the bacterial contamination of the guava in vitro establishment as well as to isolate and identify the main contaminants. The work was carried out with 34 nodal segments of guava tree which did not succeed the in vitro establishment. Twenty-eight out of them presented microbial contamination visible on the culture medium, around the base of the explants and sometimes colonizing the same ones. The cultural characters of the contaminants microorganisms in the culture medium for the in vitro establishment were described, isolated and purified. Traditional staining, physiological and biochemical tests were realized for the identification. The obtained results indicated that the microbial contamination and the fenolization limited the in vitro establishment of guava. It was determined that the 76.47% of the samples analyzed presented bacterial contamination, the 5.88% by yeasts and the 17.47% did not presented detectable contaminants. The most frequent contaminants belonged to the Pseudomonadaceae and Enterobacteriaceae families. The injurious effect of the contaminants on the explants of guava were observed and a total necrosis of the same ones was detected. Key words: bacterial contamination, Enterobacteriaceae in vitro propagation, Pseudomonadaceae, Psidium guajav