Combination of Pretreatment with White Rot Fungi and Modification of Primary and Secondary Cell Walls Improves Saccharification

Abstract

Plant cell walls have protective and structural functions conferring resistance to degradation. The lignin and hemicellulose network surrounding the cellulose microfibrils is insoluble unless subjected to harsh treatments. As lignin, pectin and xylan are effective barriers to cellulose extraction and hydrolysis, reducing their presence in cell walls improves saccharification. Microorganisms that can depolymerise lignin are of extreme interest to the biofuel industry. White rot fungi can be effective in pretreatment of lignocellulosic biomass prior to saccharification. Here, we show the cumulative effects of pretreating biomass with two white rot fungi, Phanerochaete chrysosporium and Trametes cingulata, on tobacco lines with reduced lignin or xylan, caused by suppression of the CINNAMOYL-CoA REDUCTASE, CINNAMATE-4-HYDROXYLASE, TOBACCO PEROXI-DASE 60 or UDP-GLUCURONATE DECARBOXYLASE and on Arabidopsis thaliana with reduced de-esterified homogalacturonan content, obtained by overexpressing a pectin methyl esterase inhibitor or constitutively expressing the Aspergillus nigerPOLYGALACTURONASE II gene. Tests were extended to fresh material from an Arabidopsis mutant for a cell wall peroxidase. We demonstrate that fungal pretreatment is a reliable method of improving cellulose accessibility in biofuel feedstocks, fresh material and cell wall residues from different plants. These results contribute to the understanding of the consequences of primary and secondary cell wall perturbations on lignocellulosic biomass accessibility to white rot fungi and on saccharification yield. A comparison of the effects of P. chrysosporium and T. cingulata on tobacco saccharification also highlights the limitation of current knowledge in this research field and the necessity to systematically test culture conditions to avoid generalisations.

The Pertinence of Microwave Irradiated Coconut Shell Bio-Sorbent for Wastewater Decolourization: Structural Morphology and Adsorption Optimization Using the Response Surface Method (RSM)

“…The highest colour removal of 98.46% was obtained at pH 6 but decreased to 95.69% as the pH increases to 7. Basically, the colour pigments in POME such as the phenolic, pectin and lignin, dissociate to generate negatively charged radicals in the acidic solution [ 59 ]. On the other hand, the acidic media favours the oxidation of the pretreated CSAC to acquire positive charges on the surface.…”

The Promoting Mechanism of the Sterile Fermentation Filtrate of Serratia odorifera on Hypsizygus marmoreus by Means of Metabolomics Analysis

“…These materials contain a large amount of cellulose and hemicellulose. Edible mushrooms rely on extracellular enzymes such as cellulase and xylanase to degrade cellulose and hemicellulose to produce monosaccharides that enter the central carbon metabolism (EMP, PPP, and TCA cycle) to provide energy and materials for mycelial growth and development [34,35]. In a recent study, QS autoinducers were found to increase the transcript level of lignin-degrading enzyme genes in H. marmoreus [20].…”