Background:
Recently developed iron co-catalyst enhancement of dilute-acid pretreatment of biomass is a promising approach for enhancing sugar release from recalcitrant lignocellulosic biomass. However, very little is known about the underlying mechanisms of this enhancement. Here, our aim was to identify several essential factors that contribute to ferrous ion-enhanced efficiency during dilute-acid pretreatment of biomass and to initiate the investigation of the mechanisms that result in this enhancement.
Results:
During dilute-acid and ferrous ion co-catalyst pretreatments, we observed concomitant increases in solubilized sugars in the hydrolysate and reducing sugars in the (insoluble) biomass residues. We also observed enhancements in sugar release during subsequent enzymatic saccharification of iron co-catalyst pretreated biomass. Fourier transform Raman spectroscopy showed that major peaks representing the C-O-C and C-H bonds in cellulose are significantly attenuated by iron co-catalyst pretreatment. Imaging by Prussian blue staining indicates that Fe2+ ions associate with both cellulose/xylan and lignin in the untreated as well as dilute-acid/Fe2+ ion pretreated corn stover samples. Analyses by scanning electron microscopy and transmission electron microscopy reveal structural details of biomass after dilute-acid/Fe2+ ion pretreatment, in which the delamination and fibrillation of cell wall were observed.
Conclusions:
Using this multi-modal approach, we have revealed that (1) acid-ferrous ion assisted pretreatment increased solubilization and enzymatic digestion of both cellulose and xylan to monomers, and (2) this pretreatment likely targets multiple chemistries in plant cell wall polymer networks, including those represented by the C-O-C and C-H bonds in cellulose.Source:
http://www.biotechnologyforbiofuels.com/rss/