PRODUCTION OF INDOLE-3-ACETIC ACID BY BACILLUS ISOLATED FROM DIFFERENT SOILS

G. R. Dos Santos, A. G. De Oliveira, J. Da Luz Costa, L. F. B. Chagas, L. A. De Oliveira, A. F. Chagas Junior, A. L. Lopes Da Silva

Abstract: Bacillus sp. can be found in different environments, produce endospores and being known as Plant Growth Promoting. The aim of this study was to evaluate the ability of Bacillus thuringiensis and Bacillus cereus isolated from soil samples from various regions in the State of Tocantins, in the production of auxin. Both in the absence and in the presence of L-tryptophan all bacteria tested produced auxin. The production of auxin increased with the increasing of the concentrations of L-tryptophan, especially the isolates UFT Bt 07, UFT Bc 19 and UFT Bc 20, which presented the highest levels of production. Twenty isolates, 12 (60%) had concentrations of auxin more than 100 μg mL–1. For most of the isolates the increased production of auxin occurred with 48 hours of bacterial growth. Bacilli tested have great ability to biosynthesize auxin from tryptophan as a precursor; can be considered as probable growth promoters of plant.

Keywords: indole-3-acetic acid; L-tryptophan; phytohormones; plant growth promoting rhizobacteria (PGPR); soil biology

Date published: 2017-09-11