Phenotype MicroArray™ (PM) Technology is a unique platform that can be used in bioprocess development projects with virtually any type of cell:  bacterial, fungal, or animal.   The technology allows scientists to quickly and easily culture cells under a wide range of diverse culture conditions and simultaneously examine important parameters such as in vivo pathway activities and cell productivity.  A companion instrument, the OmniLog®, can monitor 5,000 culture assays at a time and provide detailed kinetics.   PMs are sets of ~2,000 preloaded cell culture assays that are performed in a standard 96-well microplate format comprised of basic cellular nutrition assays for C, N, P, and S metabolism (800 tests), pH growth range and regulation of pH control (100 tests), sensitivity to NaCl and various other ions (100 tests), and sensitivity to chemical agents that disrupt various biological pathways (1,000 tests).  A slightly different set is available for animal cells.  The assay platform uses proprietary redox dye chemistries to measure cell respiration.  To start the assays, cell suspensions are inoculated into the wells.  As the cells grow and respire in a well, the redox dye chemistry forms increasing levels of purple color.   Examples will be presented to show how these assays can systematically analyze medium composition effects on cell growth, productivity, viability, stability/instability/differentiation, and other aspects important to bioprocess improvement.