Isolation and in vitro screening of plant growth-promoting rhizobacteria from Solanum lycocarpum St. Hil., an endemic plant of the Brazilian tropical savannah

Solanum lycocarpum St. Hil. is an endemic plant of the Brazilian tropical savannah (cerrado) that is capable of growing on acidic and nutrient-poor land, an ability which attracts attention to its rhizospheric microbiota, including plant growth-promoting rhizobacteria (PGPR). In this work, 131 bacterial strains were isolated from rhizosphere samples of S. lycocarpum and were tested in vitro for direct mechanisms of plant growth promotion (biological nitrogen fixation, phosphate solubilization and indolic compounds production) and enzyme activities. The 26 most promising isolates selected from the previous tests were used to continue the screening. Ten of these isolates showed antifungal activity against fourteen phytopathogenic fungi and twelve isolates showed antimicrobial activity against at least one of the three clinical pathogens evaluated. Seven of the 26 isolates were identified at random as belonging to the genera Bacillus, Burkholderia and Microbacterium, are PGPR and have potential to participate in more in-depth research aimed at the development of bio-inputs, especially the Bacillus strains.   Key words: Biological control, biotechnological potential, cerrado, plant growth-promoting rhizobacteria (PGPR), phytopathogenic fungi, Rhizosphere, Solanum lycocarpum St. Hil.