Resumo

Environment improvement, as well as the reduction in the uses of fossil-derived energies, had led the interest on biofuels. In Uruguay the main raw material used for biofuels production is sugarcane. However this crop has agro-climatic limitations in our country stressing the use of sweet sorghum (Sorghum bicolour) as an alternative and complementary raw source. Sweet sorghum is a multipurpose crop, used for bioethanol, energy and sugar production as well as cattle forage. This crop present optimal growth conditions in Uruguayan´s latitude, where has a wide range of soil (pH 5-8.5) adaptation, being very efficiency in water usages, features which allows it to resist long dry periods. Optimal development of this crop needs big amount of high cost chemical fertilizer inputs. In addition this process has important environmental impacts like water contamination and eutrophication. With aim to contribute with the economic and environmental sustainability of this crop in Uruguay, we propose the use of plant growth promoting bacteria (PGPB) as a bioinoculant. For that, a native probably-endophytes collection, associated with sweet sorghum variety M81E, was constructed for future biotechnology application, focused on diazotrophs. Stems and roots were surface sterilized and putative-endophytes were isolated from plants grown in high and low N content soils. Isolates obtained were genetically characterized by ERIC-PCR. In those isolates with different ERIC-pattern, plant growth promotes features like siderophore and IAA production, phosphate solubilisation, as well as putative features involved in plant-bacteria interaction, like cellulose, peroxidases and lignolases activities were screened. Isolates with more than two features mentioned were identified by 16S DNA sequencing and phylogenetic studies were carrying out. As a result of these approaches we obtained a library contained 183 putative-endophytes. Within them 18 and 22 were able to produce siderophores and solubilise phosphate respectively. In addition we obtained 3 and 5 isolates hemicellulases and cellulose producers respectively. Results obtained from phylogenetic studies will be present.