Identification of furfural as a key toxin in lignocellulosic hydrolysates and evolution of a tolerant yeast strain.
Bottom Line: One of them is the presence of inhibitors in lignocellulosic hydrolysates that are released during pre-treatment.These compounds inhibit growth and hamper the production of ethanol, thereby affecting process economics.By correlating the potential inhibitor abundance to the growth-inhibiting properties of the corresponding hydrolysates, we identified furfural as an important contributor to hydrolysate toxicity for yeast.
Affiliation: ETH Zurich, Institute of Molecular Systems Biology, Zurich, Switzerland.Show MeSH
Related in: MedlinePlus
Mentions: Based on our chemical analysis of the four hydrolysates, as well as previous toxicological investigations (Delgenes et al., 1996; Klinke et al., 2004), we chose vanillin as a representative from the phenol group and the furans furfural and 5‐hydroxy‐methylfurfural to assess toxicity in more detail. Dose–response curves of increasing inhibitor concentration on the growth rate of the yeast TMB3400 identify vanillin as the most and 5‐hydroxy‐methylfurfural as the least toxic compound (Fig. 2). The question then was whether the actual hydrolysates contained growth‐affecting concentrations of these three inhibitors. In addition to our own measurements, we also searched for reported inhibitor concentrations in published hydrolysate compositions (Table 1). The actual concentration of 5‐hydroxy‐methylfurfural in the hydrolysates was below a relevant level. Furfural and vanillin in contrast were found in concentration ranges that affect growth significantly.
Affiliation: ETH Zurich, Institute of Molecular Systems Biology, Zurich, Switzerland.