Removal of phenolic inhibitors from lignocellulose hydrolysates using laccases for the production of fuels and chemicals

Abstract

Lignocellulose is the most abundant biopolymer in the biosphere. It is inexpensive and therefore considered an attractive feedstock to produce biofuels and other biochemicals. Thermochemical and/or enzymatic pretreatment is used to release fermentable monomeric sugars. However, a variety of inhibitory by‐products such as weak acids, furans, and phenolics that inhibit cell growth and fermentation are also released. Phenolic compounds are among the most toxic components in lignocellulosic hydrolysates and slurries derived from lignin decomposition, affecting overall fermentation processes and production yields and productivity. Ligninolytic enzymes have been shown to lower inhibitor concentrations in these hydrolysates, thereby enhancing their fermentability into valuable products. Among them, laccases, which are capable of oxidizing lignin and a variety of phenolic compounds in an environmentally benign manner, have been used for biomass delignification and detoxification of lignocellulose hydrolysates with promising results. This review discusses the state of the art of different enzymatic approaches to hydrolysate detoxification. In particular, laccases are used in separate or in situ detoxification steps, namely in free enzyme processes or immobilized by cell surface display technology to improve the efficiency of the fermentative process and consequently the production of second‐generation biofuels and bio‐based chemicals.

Agricultural Wastes and Their By-Products for the Energy Market

“…Essential steps in the biogas production process, such as hydrolysis and acidogenesis, can be inhibited, resulting in a decreased conversion of organic matter into CH 4 and CO 2 . For instance, phenolic compounds and furan derivatives can inhibit key enzyme activities or microbial growth, leading to a reduced rate of substrate breakdown and biogas formation [214].…”