Effect of osmotic stress on the derepression of invertase synthesis in nonconventional yeasts

AIMS: The aim of this study was to analyse the effect of osmotic stress on the biosynthesis of invertase enzyme in nonconventional yeasts. METHODS AND RESULTS: Invertase activities of the nonconventional yeast species belonging to Kluyveromyces, Schwanniomyces and Pichia genus were measured either in the presence or in the absence of various amounts of NaCl. The effect of hyperosmotic stress on the glucose consumption of Saccharomyces cerevisiae and Pichia anomala were also compared. Like S. cerevisiae, derepression of invertase synthesis in Kluyveromyces lactis, Schwanniomyces occidentalis and Pichia jadinii is inhibited by hyperosmotic stress. However, derepression of invertase synthesis in P. anomala is not affected by hyperosmotic stress. In addition, low levels of osmotic stress activated invertase synthesis three- to fourfold in P. anomala and K. lactis. CONCLUSIONS: This study shows that low levels of osmotic stress induces the invertase synthesis at very high levels in P. anomala and K. lactis. Glucose consumption was not influenced at significant levels by the hyperosmotic stress in P. anomala. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows the activation of invertase synthesis by low levels of osmotic stress in P. anomala and K. lactis.