RESUMO
In an attempt to obtain biological control agents for controlling bacterial spot of cucumber, over 250 bacterial strains were isolated from agricultural soil samples, collected from different localities in Giza Governorate (Egypt) and screened for in vitro antibiosis towards Xanthomonas campestris. Only 2 strains showed antagonistic activity. They and their culture filtrates restricted the growth of a number of G- and G(+)-indicator bacteria. On Chrome Azurol S agar, both strains exhibited a marked siderophore production. Biolog plates identified these strains as Rahnella aquatilis. Their characteristics were studied and compared with literature data on R. aquatilis. This antagonistic bacterium has not been previously isolated in Egypt.
Assuntos
Cucumis sativus/microbiologia , Rahnella/classificação , Rahnella/metabolismo , Microbiologia do Solo , Bacteriocinas/metabolismo , Egito , Microscopia Eletrônica , Rahnella/ultraestrutura , Sideróforos/metabolismo , Xanthomonas campestris/crescimento & desenvolvimentoRESUMO
Erwinia herbicola strain 48 was isolated from diseased phaseolous seedlings and characterized by biochemical properties, cellular fatty acid analysis and SDS-PAGE of the soluble cell protein. Although cellular fatty acid profile and the soluble cellular protein pattern showed high degree of similarity in comparison to those from E. herbicola strain 347417, obtained from the International Mycological Institute U.K., plasmid profiles were different. Both strains harbor a 23.1 kb plasmid, in addition, E. herbicola 48 contains 2 more plasmids (26.8 and 32.5 kb). The antagonism of E. herbicola 48 against a number of Gram-negative and Gram-positive bacteria was tested in vitro. Only Gram-negative bacteria were inhibited, suggesting that the inhibitory factor is likely to be bacteriocin.