Maintaining recombinant plasmids in yeast or certifying the purity of yeast mutant strains often requires culture media lacking amino acids. Easy access to a variety of quality pre-made amino acid dropout mixtures simplifies the process of making selective yeast media. Using a fixed dropout base with variable pre-made amino acid mixtures is a flexible and economical way to save time and keep experiments moving forward quickly. Methionine-minus and variable adenine formulations, as well as single, double, triple and higher dropout mixtures are all available as blended powders to ensure experimental reproducibility for two-hybrid screening, expression vector maintenance and other applications. The traditional yeast nitrogen base and yeast culture grade sugars and supplements necessary to make a complete defined media for S. cerevisiae, S. pombe and other yeast strains also are available.