Characterization of endophytic, nitrogen-fixing bacteria isolated from Saccharum sp. (sugarcane) cultivated under organic fertilization or nitrogenated fertlization and no fertilization. / Caracterização de bactécias fixadoras de nitrogênio endofíticas isoladas de Saccharum sp. (cana-de-açúcar) cultivadas sob adubação orgânica ou fertilizante nitrogenado ou sem adubação.

AUTOR(ES)

Hebert Hernan Soto Gonzales

DATA DE PUBLICAÇÃO

2008

RESUMO

In the present study, endophytic bacterial diversity has been searched using both microbiologic and molecular methods. Microorganisms were isolated from sugarcane root, shoot and leaf. 150 isolates were identified by 16S rDNA sequencing. 18 genera were found and only 4 were present in sugarcane submitted to the three treatments. The greatest genera diversity was found in sugarcane submited to organic fertlization: 10 genera in sugarcane submitted to inorganic fertilization were found 11 genera and 8 genera in sugarcane without fertilization. Great part of the found genera belongs to the Enterobacteriaceae family: Klebsiella, Pantoea and Enterobacter. Some physiological characteristics were determined in the isolates. Endoglucanase was produced by 82% of the isolates from sugarcane submitted to organic fertilization. Lower activities were found in bacteria isolated from inorganic fertilization and no fertilization, respectively 54% and 48%. As far as pectinase activity is concerned, a percentage of 42%, 60% and 36% was presented by the isolates from organic fertilization, inorganic fertilization and no fertilization, respectively. The hability of phosphate solubilization was detected in 76.6% of the isolates. In sugarcane under organic fertilization a percentage of 71% was found, in bacteria from inorganic fertilization, 78%, and without fertilization, 88%. Plant colonization was determined using sugarcane plantlets inoculated with four genetically modified bactéria (GMEs), able to express the genes gfp and dsred. The colonization was evaluated by fluorescence microscopy, which showed that the endophytic bacteria expressing gfp and dsred genes had invaded roots and shoots from inoculated plants, without causing any disease symptom.

ASSUNTO(S)

dsred gfp nifh dsred bactérias endofíticas microscopia de fluorescência gfp cana de açúcar endophytic bacteria sugaecane fluorescence microscopy nifh

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