Polyphasic characterization of endophytic bacteria of sorghum grown on cerrado soil of the Goiás State - Brazil.

Sorghum is a cereal of great commercial importance adapted to the tropical and subtropical regions. Isolation of plant-associated bacteria of agronomic interest has been the subject of several research works, however, there are few studies on bacteria isolating from sorghum. The objective of this work was to characterize as plant growth promoters endophytic bacteria isolated from sorghum roots. A total of 24 isolates were selected using the NFb-lactate, LGI-P, and YM semi-selective medium. The characterization was based on the resistance to antibiotics, use of carbon sources, enzyme activity and 16S-23S intergenic analysis. The isolates were more sensitive to the antibiotic streptomycin and showed a higher capacity to produce lipases and cellulases. Carbon sources of acid nature were more restrictive to the bacterial growth. Most of the isolates (95.8%) showed catalase and urease activity, besides to be able to solubilize phosphate. Intergenic analysis (16-23S rDNA) revealed a great diversity among the isolates, with eight groups with about 60% of similarity. In this study, it was possible to identify great physiological and genetic diversity among the bacteria isolated from sorghum roots. Some of these isolates can be considered promising plant growth-promoting rhizobacteria or sources of enzymes for biotechnological use