Evaluation of indole acetic acid production and phosphorus solubilization by rhizospheric yeasts in cell free and entrapped cells

• Grant number: 15/11085-2
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): November 01, 2015
• Effective date (End): October 31, 2016
• Field of knowledge: Biological Sciences - Microbiology - Applied Microbiology
• Principal Investigator: Márcia Maria Rosa Magri
• Grantee: Luana Godoi Silva
• Home Institution: Centro de Ciências Agrárias (CCA). Universidade Federal de São Carlos (UFSCAR). Araras , SP, Brazil

Abstract

Microorganisms known as plant growth promoters (PGPM) can be found naturally in the rhizosphere of plants. Among the PGPM studied, emphasis on rhizobacteria and the mycorrhizal fungi. Some species of yeast found naturally in the rhizosphere of plants, have the ability to produce compounds that promote plant growth, but few studies on this group are obtained from the literature. Considering these aspects, the project aims is to evaluate the production of indol acetic acid (IAA) and phosphate solubilization by two strains of the specie Torulaspora globosa, in cell-free and immobilized culture in calcium alginate. For the immobilization of cells, a yeast suspension is prepared at the concentration of 107 cells, which are mixed with sodium alginate solution, being evaluated concentrations of 4%, 8% and 12%; these, in turn, will be transferred into a calcium chloride solution on magnetic stirrer, to the formation of the spheres. Both the free cells (107 cells) as spheres with immobilized cells, are used as the inoculum. The production of IAA is assessed by colorimetric technique, with the reaction of centrifuged culture medium with Salkowsky reagent; a pink color formation indicates the production of IAA, and the determination of its intensity in a spectrophotometer at 530 nm is used for quantification. Phosphate solubilization is assessed by yeast culture in medium Pikovskaya with reaction of centrifuged culture medium with reagent according to the colorimetric method molybdenum blue, with the intensity of blue reading in a spectrophotometer at 880 nm.