Aislamiento, identificación y caracterización de rizobacterias antagónicas a Sclerotium cepivorum

White rot caused by the fungus Sclerotium cepivorum causes great economic losses in the genus Allium nationwide. In this work, three rhizobacteria with antagonistic effect on this fungus were isolated, identified and characterized. 656 bacteria were isolated in soil samples from the rhizosphere of onion plants ( Allium cepa ). And in vitro antagonism to S. cepivorum was also evaluated. 23 of these isolates showed antagonistic activity with inhibition halos greater than 5 mm; three of these were greater than 20 mm; these were selected and identified as Gram positive bacilli, belonging to the genus Bacillus , B. amyloliquefaciens and B. subtilis . These rhizobacteria showed enzymatic activity of 1-aminocyclopropane 1-carboxylate deaminase, production of indolacetic acid and siderophores, as well as NaCl tolerance (up to 7.5%). Temperatures of 24 and 37 °C and humidity (50, 75 and 100%) did not affect bacterial development. Of the cellfree extracts obtained in different growth phases, the highest antifungal activity on S. cepivorum was obtained with the stationary phase extracts (16 to 24 h of incubation). Due to the attributes of these rhizobacteria they could be considered as an alternative for the control of S. cepivorum in onion.