Conclusions
This study has shown proof of principle of co-feeding formic acid to glucose fed cultivations of Y. lipolytica . This yeast species was shown to consume formic acid up to high molar ratios (>10) relative to the glucose that was fed, and be able to extract metabolic energy from it up to a formic acid:glucose ratio of about 5. While this shows that this yeast species is a good natural consumer of formic acid, there is room to benefit more of its potential.
The study also demonstrated how a fed batch process was developed and successfully executed up to pilot scale (300 l) in which co-feeding of formic acid at a formic acid:glucose molar ratio of 5 was shown to increase the yield of biomass on glucose by >20%. A dynamic fermentation process model was developed based on the initial data and subsequently applied to guide the development of the fermentation protocols by quantitatively simulating the results of experimental designs before they were executed.
We hope that this work will contribute to further developing the fermentation industry into a sector that can keep providing mankind with the required molecules for production of food, feed, materials and fuels in a truly sustainable manner.