Boron stimulates yeast (Saccharomyces cerevisiae) growth

Boron is required for the growth of vascular plants and embryonic development in fish. The molecular basis of boron's essentiality, however, remains unknown for both. The objective of this study was to determine whether yeast (Saccharomyces cerevisiae) could be used as a model for the evaluation of intracellular boron trafficking. Three experiments were conducted to assess the effect of boron supplementation on yeast growth. Cultures were grown in low boron media containing 0.04 micromol B/L. After 24 h, a new flask was inoculated with this culture; it was allowed to reach early log phase growth (9 h) and was then divided between two flasks. One flask was supplemented with ultrapure boric acid to achieve a concentration of 185 micromol B/L (+B); the other was supplemented with an equivalent volume of ultrapure water (NB). Boron significantly stimulated cell growth rate into the stationary phase of growth. Yeast cell boron concentrations decreased in both treatments over the course of the experiment, but analysis by inductively coupled plasma-mass spectrometry (ICPMS) did not detect differences in cellular concentration between the boron supplemented (B) and nonsupplemented (NB) groups. Ethanol concentrations did not differ between the two treatments, demonstrating that boron-stimulated growth was not a secondary effect of alcohol dehydrogenase inhibition. The demonstration of boron-dependent growth stimulation in yeast suggests that Saccharomyces cerevisiae can be used as a model system for the study of intracellular boron trafficking.