Evaluation of inhibition of lignocellulose-derived by-products on bioethanol production by using the QSAR method and mechanism study

To evaluate the inhibition of by-products that exist in pretreated lignocellulose hydrolysate on bioethanol fermentation, quantitative structure-activity relationship (QSAR) models were established in the present study. These models have the potential to predict the fermentation inhibition to minimize the experimental effort. They also provided an innovative methodology for removing fermentation inhibitors purposefully and for optimizing pretreatment parameters and thus could enhance the bioethanol yield. The results indicated that the fermentation inhibition of phenolic aldehyde were stronger than that of phenolic acid followed by phenolic alcohol in which the fermentation inhibition was weakened by the existence of the methoxy group in the benzene ring. Meanwhile, the formation of the intramolecular hydrogen bonds of fermentation inhibitors also played an important role in weakening their fermentation inhibition. The individual fermentation inhibition of fermentation inhibitors was found strongly related to their molecular descriptors. Furthermore, ferulic acid was chosen as the representative inhibitor for the primary investigation on the combined fermentation inhibition of the various complex binary fermentation inhibitor mixtures, which co-existed in the lignocellulose hydrolysate. As indicated by the results, antagonism occurred mainly under the higher ferulic acid concentrations in the binary mixtures, while a simple additive effect was generated.