MARRIEL, I. E.

NEVES, A. A.

NEVES, A. L.

OLIVEIRA, A. C. de

OLIVEIRA-PAIVA, C. A.

SCHAFFERT, R. E.

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40PS3-12 Metabolic diversity of diazotrophlc bacteria isolates from Brazilianmaize and sorghum culUvars by the blolog systemIvanildo Evódio Marriel1, A. Ump Neves 1, A. Aparecida Neves 1, A.C. de Oliveira 1, C. AbreuOliveira2, and R. Schaffert1lEMBRAPA Maize anel Sorghum. anel 2eentro Universitário Monsenhor Meaaiaa, Sete Lagoas, MG, BrazilBrazil is an emerging agricultural power potential of millions of hectares available for agriculturalexpansion. The main chaHenge of the Brazilians is to keep the high productivity of the agrobusiness,and stil! keep the environmental, economic, and social pressures under control. Biological nitrogenfixation in assoclation with maize and sorghum plants offers an economically attractive andecologically sound means for sustainability agriculture. The present study 'lias conducted to evaluatethe variability among diazotrophic bacterla trom maize (M) and sorghum (S) grown under differentedafoclimatic conditions. Diversity of 47 isolates of diazotrophic bacteria, with variable morphoJogiçalcharacteristics obtained tom roots (R), sap (S), silk (E), and trom immature maize grains (G), wasdetermined based on differential carbon substrate utilization profile by the BioJog system with GN2Microplates. The resulting differences were anaJyzed using Jaccard's similarity coefficlent and UPMGclustering. Diversity was calculated using the Shannon index. Dendrograrns 01 metabolic diversitydata (presence or absence 01 growth in different carbon substrates) revealed that the isolates areclassified into nine apparent clusters. Cluster A comprises 31 isolates; cluster B inclucles one isolate;cluster C, two isolates (MR10 and SR6); cluster O, two isolates (SS2 and S$3); cluster E, threeisolates (MR6, MG1, and MR7); cluster F, four isolates (MG2, MR8, A11, and A12); cluster G, oneisolate (MS9), and cluster Hwith three isoJates (MR1, ME, and MR9). In a comparative analysis withstandard species, 66% of the strains were similar with Azospirillum brasilense (cluster A) and only4% were more similar to Azospirillum lipoferum (cluster F). Resulls showed a high biocflVersityamongthe different strains, but no correlation between the phenotypic groups and the origin of the strainswas observed. Selected strains were subcultured for identification by 168 rDNA sequencing.Session 3: Plant growth promotion of diazotrophs

Metabolic diversity of diazotrophic bacteria isolates from Brazilian maize and sorghum cultivars by the biolog system.

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