Ethyl acetate extracts from superimposed liquid concentrated cell cultures of Azotobacter chroococcum, Azotobacter vinelandii, Pseudomonas aeruginosa, Pseudomonas putida, Serratia sp. and Kleb- siella pneumoniae strains, obtained from rhizosphere of rice cultivated in the Tolima region, Colombia S. A., have shown to be pr oducers of extra cellular indole-3-acetic acid (IAA) at concentrations from 3.5 mg/ mL to 32.2 mg/l. A. vinelandii, and K. pneumoniae yielded the highest concentrations. Pseudomonas sp. was found in vitro to antagonize the Phytophthora infestans, mainly by production of siderophores under low presence of iron. Colonization of hyphae and production of antibiotics were additional activities ob- served.