Glucose/Furfural Substrate Mixtures in Non‐Engineered Yeast: Potential for Massive Rerouting of Fermentation to C−C Bond Formation on Furfural

Suitable mixtures of glucose and furfural may provide novel strategies for C−C bond formation on furfural due to the versatility of low‐cost biological catalysts. We use in‐cell NMR with non‐engineered commercial yeast as the catalyst to determine the interplay between furfural and glucose metabolism in non‐engineered yeast. The presence of furfural is shown to modulate kinetic barriers in glucose conversion and to favor the accumulation of acetaldehyde in situ. As a result, glucose carbons are remarkably strongly redirected towards C−C bond formation between furfural and a glucose‐derived C2 unit. In the presence of suitable glucose/furfural substrate mixtures in non‐engineered yeasts, glucose carbons can achieve relative influxes of at least 80 % into the C−C bond formation on furfural, compared to only 20 % into ethanol. Chain‐elongation of furfural by yeast thus seems a viable strategy for the upgrading of lignocellulosic biomass through concurrent conversion of furfural and glucose. The product is related to chemicals that already have found value in the fine chemical and pharmaceutical industries. Furfural and Glucose Conversion in Non‐Engineered Yeast: Glucose/furfural substrate mixtures can be concurrently upgraded by whole cell catalysis. Through in situ production and interception of pyruvate/acetaldehyde in non‐engineered yeast, such substrate mixtures can efficiently be used for C−C bond formation on furfural using whole‐cell catalysis, while ethanol and glycerol formation can be vastly suppressed.