Study of endophytic bacteria isolated from commercial rice cultivation with growth promoting activity properties

Abstract

In this study, the growth-promoting activity of endophytic bacteria isolated from different tissues of rice varieties from the municipality of Montería, department of Cordoba, Colombia, was evaluated in vitro. The population of endophytic bacteria was isolated on R₂A agar culture medium, counted and qualitatively evaluated for nitrogen fixation, phosphate solubilization and siderophore production. Endophytic bacteria with positive activities were identified by 16S rRNA gene sequencing with 5 sets of oligonucleotides specific for the class firmicutes, beta-proteobacteria; gamma-proteobacteria; alpha-proteobacteria and actinobacteria. A total of 107 isolates of endophytic bacteria were isolated, with the highest occurrence in variety 2000 and the lowest in variety 67; the most colonized tissue was the root. Of the 22 isolates, 11 showed the ability to solubilize phosphate, 6 to produce siderophores, and 5 to fix nitrogen. Sequencing results proved the identity of Bacillus cereus and Bacillus thuringiensis, which have the ability to promote growth in rice by phosphate solubilization, nitrogen fixation and siderophore production.