Do psychrotolerant Patagonian soil yeasts produce 3-indole acetic acid?

Plant growth promoting microorganisms play a substantial role in current plant production practices. Yeasts have shown a promising role in enhancing plant production. We studied the production of indole 3-acetic acid (IAA)-like compounds in three psychrotolerant Patagonian native yeast strains. The yeast Tausonia pullulans CRUB 1772, Candida saitoana CRUB 1770 and Saccharomyces eubayanus CRUB 2014 were evaluated using the Salkowski's colorimetric technique and high-performance liquid chromatography (HPLC). T. pullulans CRUB 1772 was the highest producer of IAA-like compounds using the colorimetric technique. Nevertheless, none of the tested yeasts reached the production level of the bacterial strain A. argentinense Az39 used as positive control. The HPLC analysis revealed that only C. saitoana CRUB 1770 and S. eubayanus CRUB 2014 were able to truly produce IAA. Other peaks were also observed, which might correspond to intermediate compounds within the IAA biosynthetic pathway.