Towards closed carbon loop fermentations: Cofeeding of Yarrowia lipolytica with glucose and formic acid

Abstract

A novel fermentation process was developed in which renewable electricity is indirectly used as an energy source in fermentation, synergistically decreasing both the consumption of sugar as a first generation carbon source and emission of the greenhouse gas CO2. As an illustration, a glucose‐based process is co‐fed with formic acid, which can be generated by capturing CO2 from fermentation offgas followed by electrochemical reduction with renewable electricity. This “closed carbon loop” concept is demonstrated by a case study in which cofeeding formic acid is shown to significantly increase the yield of biomass on glucose of the industrially relevant yeast species Yarrowia lipolytica. First, the optimal feed ratio of formic acid to glucose is established using chemostat cultivations. Subsequently, guided by a dynamic fermentation process model, a fed‐batch protocol is developed and demonstrated on laboratory scale. Finally, the developed fed‐batch process is tested and proven to be scalable at pilot scale. Extensions of the concept are discussed to apply the concept to anaerobic fermentations, and to recycle the O2 that is co‐generated with the formic acid to aerobic fermentation processes for intensification purposes.

Synthetic methylotrophic yeasts for the sustainable fuel and chemical production

“…It was shown that co-feeding formate and glucose, up to a molar ratio of ~ 5:1, linearly increased the biomass yield of Y. lipolytica . Consistent with previous observations in other yeasts, it is hypothesized that consumption of formate under these conditions has a positive net ATP yield and therefore promotes growth [ 133 ]. While both examples are first steps towards the efficient utilization of formate in yeasts, there is still room to better exploit its potential.…”