A myo-inositol bioassay utilizing an auxotrophic strain of S. cerevisiae.

Myo-inositol is a six‑carbon sugar that is essential for the growth of mammalian cells and must be obtained through either extracellular uptake or de novo biosynthesis. The physiological importance of myo-inositol stems from its incorporation into phosphoinositides and inositol phosphates, which serve a variety of signaling, regulatory, and structural roles in cells. To study myo-inositol metabolism and function, it is essential to have a reliable method for assaying myo-inositol levels. However, current approaches to assay myo-inositol levels are time-consuming, expensive, and often unreliable. This article describes a simple new myo-inositol bioassay that utilizes an auxotrophic strain of S. cerevisiae to measure myo-inositol concentration in solutions. The accuracy of this method was confirmed by comparing assay values to those obtained by tandem mass spectrometry (LC-MS/MS). It is easy to perform, inexpensive, does not require sophisticated equipment, and is specific for myo-inositol.