Glutathione production from mannan-based bioresource by mannanase/mannosidase expressing Saccharomyces cerevisiae.

This work aims to produce glutathione directly from mannan-based bioresources using engineered Saccharomyces cerevisiae. Mannan proved to be a valuable carbon source for glutathione production by this organism. Mannan-hydrolyzing S. cerevisiae was developed by heterologous expression of mannanase/mannosidase on its cell surface. This strain efficiently produced glutathione from mannose polysaccharide, ß-1,4-mannan. Furthermore, it produced glutathione from locust bean gum (LBG), a highly dense and inexpensive mannan-based bioresource, as sole carbon source. Glutathione productivity from LBG was enhanced by engineering the glutathione metabolism of mannan-hydrolyzing S. cerevisiae. Expression of extracellular mannanase/mannosidase protein combined with intracellular metabolic engineering is potentially applicable to the efficient, environmentally friendly bioproduction of targeted products from mannan-based bioresources.

Enhanced production of para-hydroxybenzoic acid by genetically engineered Saccharomyces cerevisiae.

Saccharomyces cerevisiae is a popular organism for metabolic engineering; however, studies aiming at over-production of bio-replacement precursors for the chemical industry often fail to overcome proof-of-concept stage. When intending to show real industrial attractiveness, the challenge is twofold: formation of the target compound must be increased, while minimizing the formation of side and by-products to maximize titer, rate and yield. To tackle these, the metabolism of the organism, as well as the parameters of the process, need to be optimized. Addressing both we show that S. cerevisiae is well-suited for over-production of aromatic compounds, which are valuable in chemical industry and are particularly useful in space technology. Specifically, a strain engineered to accumulate chorismate was optimized for formation of para-hydroxybenzoic acid. Then a fed-batch bioreactor process was developed, which delivered a final titer of 2.9 g/L, a maximum rate of 18.625 mgpHBA/(gCDW × h) and carbon-yields of up to 3.1 mgpHBA/gglucose.