L-ascorbic acid producing yeasts learn from plants how to recycle it.

Abstract Microorganisms employed in industrial fermentation processes are often subjected to a variety of stresses that negatively affect growth, production and productivity. Therefore, stress robustness is an important property for their application. Reactive Oxygen Species (ROS) accumulation is a common denominator to a lot of these stress factors. Ascorbic acid ( l -AA) acts as ROS scavenger, thus potentially protecting cells from harmful oxidative products. We have previously reported the development of Saccharomyces cerevisiae strains able to produce l -AA. This was obtained by expressing the known plant pathway genes and by complementing the missing step with an animal activity. Here, we show that l -AA accumulation inside yeast cells can be improved by expressing the complete biosynthetic plant pathway and, even further, by recycling its oxidation products. These new strains can be seen in a double perspective of exploitation: as novel organisms for vitamin C production and as novel cell factories for industrial processes.