Green methods of lignocellulose pretreatment for biorefinery development

Abstract

Lignocellulosic biomass is the most abundant, low-cost, bio-renewable resource that holds enormous importance as alternative source for production of biofuels and other biochemicals that can be utilized as building blocks for production of new materials. Enzymatic hydrolysis is an essential step involved in the bioconversion of lignocellulose to produce fermentable monosaccharides. However, to allow the enzymatic hydrolysis, a pretreatment step is needed in order to remove the lignin barrier and break down the crystalline structure of cellulose. The present manuscript is dedicated to reviewing the most commonly applied “green” pretreatment processes used in bioconversion of lignocellulosic biomasses within the “biorefinery” concept. In this frame, the effects of different pretreatment methods on lignocellulosic biomass are described along with an in-depth discussion on the benefits and drawbacks of each method, including generation of potentially inhibitory compounds for enzymatic hydrolysis, effect on cellulose digestibility, and generation of compounds toxic for the environment, and energy and economic demand.

Engineering Potato Virus X Particles for a Covalent Protein Based Attachment of Enzymes

“…The SC sequence was synthetized by Eurofins Genomics (Ebersberg, Germany). For in planta expression, the sequences of T. reesei endoglucanase Cel12A, the flexible glycine-serine linker (G 4 S) 2 and SC were amplified from pET22b-Cel12A-G 4 S-SC-His (Röder, unpublished data) using primers PciI-Cel12A and SC-NotI. For the production of monomeric ST-CP fusion proteins, the ST-CP sequence was amplified from pPVX-ST-CP using primers NcoI-ST and pCP-Stop-SalI.…”

“…Lignocellulose from plant residues can be converted into fermentable sugars for biofuel production, but the complex structure of the plant cell wall must be pretreated to remove lignin and ensure access for the cellulolytic enzymes . Enzymatic cellulose degradation is achieved naturally by many bacteria and fungi using multiple synergistic cellulases, including β‐1,4‐endoglucanases, β‐1,4‐exoglucanases, and β‐ d ‐glucosidases .…”

“…Lignocellulose from plant residues can be converted into fermentable sugars for biofuel production, but the complex structure of the plant cell wall must be pretreated to remove lignin and ensure access for the cellulolytic enzymes. [1][2][3] Enzymatic cellulose degradation is achieved naturally by many bacteria and fungi using multiple synergistic cellulases, including β-1,4-endoglucanases, β-1,4-exoglucanases, and β-d-glucosidases. [4][5][6][7] Research has focused on the expression of recombinant cellulases from diverse origins and on the optimization of such enzymes, e.g., for thermostability or salt tolerance.…”

Progress and perspective on lignocellulosic hydrolysate inhibitor tolerance improvement in Zymomonas mobilis

“…Generally, they can classified into four categories: physical methods including mechanical comminution, extrusion, and irradiation; chemical methods including acid pretreatment (dilute acid or concentrated acid), alkaline pretreatment, oxidation, organosolv, and ionic liquids (ILs) pretreatment; physico-chemical methods including steaming or steam explosion (STEX), ammonia fiber explosion (AFEX), liquid hot water (LHW), and CO 2 explosion; and biological methods, which use microorganisms or enzymes to degrade lignocellulosic materials. Different pretreatment methods with regard to their features, advantages, and disadvantages as well as their impact on lignocellulosic materials have been discussed in detail in other reviews (Baral et al 2014;Capolupo and Faraco 2016;Silveira et al 2015;Sun et al 2016). During the pretreatment process, a number of degradation products of lignin and sugar are generated, which could have detrimental effects on subsequent enzymatic hydrolysis and microbial cell fermentation (Jönsson et al 2013).…”

Agrowastes as Feedstock for the Production of Endo-β-Xylanase from <b><i>Cohnella</i></b> sp. Strain AR92

“…For this goal, the search and description of novel enzymes and microorganisms able to degrade plant biomass comprise a key strategy in for developing environmentfriendly bioprocesses [Capolupo and Faraco, 2016]. Lignocellulosic biomass degradation is carried out by cooperative action among microorganisms to achieve the complete deconstruction of the plant cell wall.…”