Enzymes – Key Elements of the Future Biorefineries

Abstract

The biorefinery concept in its modern meaning has emerged after it has become apparent that biofuel production from non-food biomass is struggling for economic viability. Lignocellulosic biomass is more recalcitrant and more complex than the starch-based feedstocks used for food. The former, therefore, calls for a more complex approach to its utilization. This chapter reflects MetGen’s vision of the future development of biorefineries. We will discuss the zero-waste approach to lignocellulosic biomass utilization and various ways to valorize the resulting streams to boost the economic viability of the biorefinery. We will mostly explore the relevant enzyme-based approaches and will make a special focus on lignin valorization. Enzymatic and cell-based approaches to sugar valorization will be discussed as well.

A guide to lignin valorization in biorefineries: traditional, recent, and forthcoming approaches to convert raw lignocellulose into valuable materials and chemicals

“…111,112 Recently, a LHW process was successfully applied to sowood biomass and scaled up to industrial scale in the Sweetwood plant by Fibenol in Estonia, representing the rst of its kind industrial scale biorenery aiming at producing high quality lignin and sugar hydrolysates. 113 Although LHW pretreatment solubilizes only a limited amount of lignin, it causes considerable modications of the lignin chemical structure. Most prominently, b-O-4 ′ ether linkages undergo acid-catalyzed cleavage, as illustrated in Fig.…”

“…111,112 Recently, a LHW process was successfully applied to softwood biomass and scaled up to industrial scale in the Sweetwood plant by Fibenol in Estonia, representing the first of its kind industrial scale biorefinery aiming at producing high quality lignin and sugar hydrolysates. 113…”

Utilising Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to track the oxidation of lignin by an alkaliphilic laccase

“…38 Conversely, the extraction of lignin using organosolv methods yield lignin more akin to lignin's natural form 39,40 and therefore a less complex chemical diversity which is more readily amenable to a range of analytical methods. Within this study we use a lignin derived from the liquid hot water pre-treatment and enzymatic bioprocessing of Betula pendula, [41][42][43] European white birch, with the chemical diversity arising from this lignin extraction method still a relative unknown. Although, it has been highlighted that LHW processing can result in the cleavage of β-O-4 ether linkages which can in turn transform into enol-ether compounds or repolymerise into other structures.…”

Factors that influence the activity of biomass-degrading enzymes in the presence of ionic liquids—a review

“…However, a depolymerization method is still needed to refine the biomass. Of these depolymerization methods, enzyme mediated depolymerization is gaining traction as a viable commercial scale method (Birikh et al, 2022;Dhawane et al, 2022;Climent Barba et al, 2022). A primary advantage of using enzyme catalyzed processing of any material, including biomass is the lack of off target products.…”