Solvent‐Free Enzyme Activity: Quick, High‐Yielding Mechanoenzymatic Hydrolysis of Cellulose into Glucose

Abstract

Mechanochemistry enables enzymatic cleavage of cellulose into glucose without bulk solvents,a cids,o ther aggressive reagents,o rs ubstrate pre-treatment. This clean mechanoenzymatic process (coined RAging) is also directly applicable to biomass,avoids many limitations associated with the use of cellulases,a nd produces glucose concentrations greater than three times that obtained by conventional methods.

Mechanoenzymatic Breakdown of Chitinous Material to N‐Acetylglucosamine: The Benefits of a Solventless Environment

“…Furthermore, the absence of solventt ranslates into am uch smaller total reaction volume, which facilitates manipulation while generating less waste, and enables reactions of poorly soluble and recalcitrant substrates such as chitin and cellulose. [46] These advances may offer cost-effective sustainable strategies to transform waste into useful chemicals.…”

“…Water is an essential substrate for chitinase activity and was also used as the liquid additive in LAG. [34,38,46] The amount of water in LAG was optimized by varying the ratio of liquid volumetot he weightoft he reaction mixture (h) [34][35][36] from 0t oa pproximately 3 mLmg À1 ,w hich revealed that the yield reached ap lateaua th % 1.7 mLmg À1 (i.e., 500 mLw ater per 300 mg reaction mixture;F igure 2A). [56] Such water loading is consistent with LAG conditions previously reported in mechanochemical reactions [34][35][36] and produces a moist solid-an initial texture that was also optimal for the hydrolysis of cellulose by cellulases through RAging ( Figure S6 in the SupportingI nformation).…”

“…It was recently shown that enzymes can retain activity under mechanochemicalconditions, [37][38][39][40][41][42] and our group has reported that efficient mechanoenzymatic hydrolysis of cellulose can be achieved by repeating cycles of millinga nd aging (static incubation) [43][44][45] of physical mixtures of the solid substrate, lyophilized cellulase enzymes,a nd as mall amount of water.T his process, termed reactive aging (RAging), led to significantly higher glucosec oncentrationst han previously reported methods and, importantly,w ithoutt he need for biomass pretreatment or the use of harsh chemicals. [46] Because the amount of water in RAging is orders of magnitude lower than in conventional solution processes and stoichiometrically comparable to that of the substrate, we speculated that RAging should provide am ore suitable environmentf or chitinase activity compared with conventionalb iocatalysis.…”

Thermal and Mechanical Stability of Immobilized Candida antarctica Lipase B: an Approximation to Mechanochemical Energetics in Enzyme Catalysis.

“…[35,36] In this regard, the stability of enzymes under mechanical stress has been confirmed using continuous grinding processes or mechanochemical activation followed by static incubation (RAging) with excellent results. [37,38] Nevertheless, no detailed information concerning the effect of milling on the degree of denaturation, the parameters and conditions affecting enzyme efficiency, or changes in the structure of CALB have been disclosed.…”

Dry Chemistry of Ferrate(VI): A Solvent‐Free Mechanochemical Way for Versatile Green Oxidation

“…Thes tructure of K 2 FeO 4 solid was characterized with X-ray diffraction ( Figure S3), scanning and transmission electron microscopy (SEM and TEM), revealing that the purple-black crystalline powder was composed of large plate crystals on the scale of several to dozens of mm( Figures 1b,S 4). Fors olid-state reactions of such crystalline oxidizer,t he reactivity is predefined by the exposed facets.S elected area electron diffraction (SAED) patterns were obtained on ferrate(VI) for the first time,which confirmed the single-crystalline nature of the individual plates and disclosed that K 2 FeO 4 crystals predominantly exposed the low-index {001} planes (top and bottom facets) with side planes of {200} and {010} jointed by small {210}, as shown in Figure 1c.Considering its large crystal size and that crystal particles preferentially expose the planes with low surface energy (and expected low reactivity), [13] such as the {001} planes of K 2 FeO 4 ,mechanical milling was employed to crush the original crystals and continually generate reactive fracture surface to participate into redox reactions.A nother merit of mechanochemistry is the ability to promote reactions under solvent-free conditions, [14] which is particularly beneficial for reactants like K 2 FeO 4 that lack solubility in media.…”