Automated screening in environmental arrays allows analysis of quantitative phenotypic profiles in Saccharomyces cerevisiae

Abstract

A methodology for large-scale automated phenotypic profiling utilizing quantitative changes in yeast growth has been tested and applied to the analysis of some commonly used laboratory strains. This yeast-adjusted methodology is based on microcultivation in 350 microl liquid medium, where growth is frequently optically recorded, followed by automated extraction of relevant variables from obtained growth curves. We report that cultivation at this micro-scale displayed overall growth features and protein expression pattern highly similar to growth in well aerated medium-scale (10 ml) culture. However, differences were also encountered, mainly relating to the respiratory potential and the production of stress-induced proteins. Quantitative phenotypic profiles for the laboratory yeast strains W303, FY1679 and CEN-PK.2 were screened for in environmental arrays, including 98 different conditions composed of low, medium and high concentrations of 33 growth inhibitors. We introduce the concepts phenotypic index(rate) and phenotypic index(stationary), which relate to changes in rate of growth and the stationary phase optical density increment, respectively, in a particular environment relative a reference strain. The laboratory strains presented selective phenotypic profiles in both phenotypic indexes and the two features appeared in many cases to be independent characteristics. We propose the utilization of this methodology in large-scale screening of the complete collection of yeast deletion mutants.