Identificação molecular e caracterização bioquímica de bactérias endofíticas associadas à cultura do pinhão-manso (Jatropha curcas L.) com potencial biotecnológico

Abstract

The Jatropha (Jatropha curcas L.), which belongs to the the family of Euphorbia is a plant genetically close to the Castor Plant (Ricinus communis l.), coming from Central America and being currently distributed in all tropical regions of the globe. In Brazil, this crop has received special attention as an alternative for the supply of vegetable oil as a raw material for biodiesel manufacturing, due to the biotechnological potential of its seeds. Several studies aimed at climatic adaptations and productivity have been developed on genetic variability of J. curcas; but few studies have been developed focusing on the analysis of the microbial community associated with this species. The interior of the plant is inhabited by endophyte microorganisms, which can be isolated from disinfected surface and do not put on risk the plant tissues of the host plant. This group of microorganisms has the ability to stimulate the growth of plants by direct mechanisms, such as/biological fixation of nitrogen, solubilization of inorganic phosphate indole acetic acid production (AIA) and indirect mechanisms, such as the antagonism towards phytopathogens. Moreover, endophytic microorganisms are considered promising for bioprospecting of enzymes. The aim of this study was to perform the characterization of seventy-two endophytic bacteria associated with the J. curcas plants, with potential for promoting plant growth and enzyme production. Of this total of tested isolates 40% showed positive results for fixation of atmospheric nitrogen, 43% solubilized inorganic phosphate, 69% have produced AIA, 36% showed some antagonistic activity to phytopathogenic fungi Alternaria alternata, 12% for Ceratocystis paradoxa, 22% for Fusarium proliferatum and 23% for Fusarium verticillioides. Regarding enzymatic activity, 16% of the isolates evaluated showed amyloid activity, 29% endoglycolytic, 29% lipolytic, 20% esterase, 46% pectinolytic (18% poligalacturonase and 43% pectato lyase) 37% proteolytic. From a collection of seventy two bacterial isolates, twenty-five were identified by means of the partial 16S rDNA gene embracing seven different genres: Bacillus, Citrobacter, Curtobacterium, Enterococcus, Microbacterium, Promicromonosporaceae and Sanguibacter were isolated as endophytic bacteria of Jatropha.