Evaluation and selection of culture media for the detection of auxin-like compounds and phosphate solubilization on soil yeasts.

The detection of characteristics associated with plant growth promotion has been studied frequently on bacteria and some of these detection methods were also used on yeasts. Sometimes, these methods, designed for prokaryotes, were used with no prior analysis regarding growth and production on eukaryotes. The aim of the present study was to assess and select the best suitable media for the detection of auxin-like compound production and inorganic-P solubilization on yeast strains. Already published media and new formulations, as well as yeasts with different genetic backgrounds were used for the comparison. Media were selected based on the adequate growth of yeast strains and reliable recognition of the studied features either by an easy detection of the metabolite (color or halo production) or simple medium preparation (low number of reagent and regular autoclaving). We propose here the use of the new DEV medium with glucose and with tryptophan to identify auxin-like compounds producers; and CPM medium (a variation from Custer's Chalk Medium) as base medium to identify yeasts capable of inorganic-P solubilization.