Introduction:

The use of Plant Growth Promoting Bacteria (PGPB) allows for diminishing the use of chemical products in agriculture. These products are dangerous for environments and human health. The objective of the present work was to characterize isolates from Bacilli class to select potentially efficient strains for their use in sustainable agriculture.

Methods:

To isolate bacteria; the samples from rhizosphere and rice, maize and coffee plants were heated to 80 ºC. The isolates were characterized according to PGPB and antagonistic traits. Several strains were selected to study the colonization, diversity and their effect on plant growth.

Results:

One hundred forty-five aerobic Gram-positive endospore forming bacteria were isolated from rice, maize and coffee. The studied strains showed several traits for plant growth. In thirty-seven selected strains from rice, maize and coffee, antagonistic activity was demonstrated against phytopathogenic fungi. After that, two strains were selected and they show their ability to colonize rice plants, move and form biofilms. The promised strains were identified as belonging to Bacillus genus by DNAr 16S sequencing. The molecular study of Bacillus from rice demonstrated the high genetic diversity and the occurrence of virulence determinants in few strains. The inoculation of maize and tomato in semicontrolled conditions showed positive effects in plant growth. Conclusions: An integrally characterized bacterial native collection, efficient for plant growth promotion and antagonistic activity is available, which constitutes the base for new bioproducts obtainment. This work proposes an efficient methodology for prospecting and characterizing Bacillus for their use in agricultural sustainability.

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