Biosorption of inhibitors generated in the pretreatment of lignocellulosic biomass in biorefineries

Abstract

The processing of lignocellulosic biomass in biorefineries can release compounds that act as inhibitors of the enzymatic hydrolysis and alcoholic fermentation steps. Among these inhibitors, the phenolic compounds originated from lignin degradation can inhibit or deactivate the enzymes during the hydrolysis reaction, significantly impacting the overall yield of the conversion of plant biomass into soluble sugars. Therefore, new strategies that contribute to mitigate the negative effect of these inhibitors are necessary to enable the viability of future biorefineries. In this context, a potential strategy is the use of microbial biomass as a biosorbent for the removal of the phenolic compounds generated in the pretreatment stage. Thus, the present project aims to evaluate the use of Aspergillus niger microbial biomass for adsorption of the phenolic compounds present in the liquor of the hydrothermal pretreatment of the sugarcane lignocellulosic biomass. This strategy considers that such bioadsorbent will not have any additional costs, since A. niger microbial biomass could be generated within the biorefinery as a co-product of the cellulolytic enzymes or organic acids production processes. In order to achieve this goal, the methodology includes the fungi cultivation to obtain the microbial biomass, the treatment of the biomass to be applied as a bioadsorbent, followed by the adsorption tests of the phenolic compounds. The bioadsorbent will be characterized by pore structure, functional groups and surface charge. In addition to the adsorption conditions study (charge, temperature and pH), adsorption kinetics and isotherms will also be obtained for the selected conditions. This proposal is linked to the thematic project of the BIOEN/FAPESP program: "From the cellular plant to the integrated biorefinery biodiesel-bioethanol: a systemic approach applied to complex problems in micro and macro scales" (proc. 2016/10.636-8). (AU)