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In this work, the performance of a fed-batch high solids enzymatic hydrolysis of plantain pseudostem was studied at different particle sizes. The plantain pseudostem was pretreated with an alkaline hydrogen peroxide medium. Two set of experiments were carried out in a stirred tank bioreactor at substrate concentrations of 10% and 15% w/v, combined each one with particle sizes #20–40, #40–60, and # > 100, in 1 L of reaction volume. Particle sizes of #20–40 and #40–60 allowed around 99% of holocellulose conversion with a substrate concentration of 10% w/v, and 91% with 15% w/v; meanwhile enzymatic hydrolysis at particle size of mesh # > 100 yielded 70% and 73%, with a substrate concentration of 10% and 15% w/v, respectively. The conditions recommended for enzymatic hydrolysis at high solids of 15% w/v through fed-batch operation are particle size #20–40 and 6 h of reaction, achieving 91% of holocellulose conversion and 82 g/L of reducing sugars. [ABSTRACT FROM AUTHOR]

Liquid hot water extraction followed by mechanical extrusion is a promising chemical-free pretreatment for cellulosic ethanol production from rigid hardwood. To alleviate the heavy dependence on chemical input of chemical pretreatments and make a better use of current idle thermo-mechanical pretreatment plant for mechanical pulp, a sequential chemical-free pretreatment approach, i.e., liquid hot water extraction followed by mechanical extrusion was investigated in this work. Its ability to fractionate hemicellulose while facilitating cellulose hydrolysis of rigid eucalyptus and aspen hardwood was assessed. The structural changes of lignin during liquid hot water extraction were elucidated using spectrum analysis. Cellulose accessibility to hydrolytic enzymes, cellulose hydrolysis yields and fermentation potential were also assessed. Results showed that the mild liquid hot water extraction recovered 54.0% and 38.1% of xylan hemicellulose from eucalyptus and aspen hardwood respectively, while causing limited lignin condensation reactions. Extending liquid hot water extraction time from 45 to 90 min significantly facilitated the subsequent mechanical deconstruction of both wood substrates without compromising their overall carbohydrate recovery. A maximum cellulose hydrolysis yield of 79.6% and nearly 100% (10 w/v solids loading, enzyme dosage, 20 mg g−1 cellulose) was observed on eucalyptus and aspen substrate respectively, which were feasible for further fermentation process. This work showed liquid hot water extraction followed by mechanical extrusion was a feasible pretreatment strategy for bioethanol production even the starting wood chip substrate was highly rigid. [ABSTRACT FROM AUTHOR]

The aim of this study was to explore the efficiency of a mechano-enzymatic deconstruction of two macroalgae species for sugars and bioethanol production, by using a new enzymatic cocktail (Haliatase) and two types of milling modes (vibro-ball: VBM and centrifugal milling: CM). By increasing the enzymatic concentration from 3.4 to 30 g/L, the total sugars released after 72 h of hydrolysis increased (from 6.7 to 13.1 g/100 g TS and from 7.95 to 10.8 g/100 g TS for the green algae U. lactuca and the red algae G. sesquipedale, respectively). Conversely, total sugars released from G. sesquipedale increased (up to 126% and 129% after VBM and CM, respectively). The best bioethanol yield (6 geth/100 g TS) was reached after 72 h of fermentation of U. lactuca and no increase was obtained after centrifugal milling. The latter led to an enhancement of the ethanol yield of G. sesquipedale (from 2 to 4 g/100 g TS). [ABSTRACT FROM AUTHOR]

The hierarchical structure of wood cell walls resulting from complex arrangement and distribution of the heterogeneous components is considered to impact significant impediment to enzymatic hydrolysis of cellulose for biofuels. In this work, micronized wood with significant cell wall ultrastructural deconstruction were effectively produced from ring and puck milling within 12 min. In a subsequent enzymatic hydrolysis, micronized wood resulted in increase of cellulose hydrolysability by 4–14 folds over that of starting material. The underlying mechanism towards facilitating enzymatic hydrolysis was studied through delineating the ultrastructural changes and alternation of cellulose chemistry in micronized wood cell wall using SEM, TEM, CLSM, GPC, XRD, HPLC and Simon’s staining techniques. Electronic microscopy revealed distinct stages of wood cell wall deconstruction that was coincident with particle size reduction, including cell fracture and delamination, cell wall disintegration, and amorphization of cell wall fragments. Simons’ staining results also indicated increasing substrate accessibility and porosity of micronized wood, likely due to the ultrastructure alternation of cell walls. GPC and XRD revealed significant decrease of cellulose degree of polymerization (DP) and crystallinity. The correlation of these factors with cellulose hydrolysability was studied and further arranged in order through principal component analysis. The major positive factors affecting hydrolysability were surface accessibility and porosity, while cellulose crystallinity and DP were the major negative factors accompanied by particle size. The established weighed order of factors behind hydrolysability provides insights of lowering cell wall structural recalcitrance by mechanical manner. [ABSTRACT FROM AUTHOR]

In this study, we determined the effect of organosolv pretreatment on herbaceous biomasses corn stover and wheat straw, by using high-concentration ethanol as the solvent. A high-concentration of ethanol allows for the easy reuse and recycling of the solvent. First, we tested the effects of ethanol pretreatments at 60 and 99.5% (w/w) and found that highest solvent concentration resulted in low glucose digestibility. The maximum enzymatic glucose digestibility with 60% ethanol was 92.6% at 190°C for 120 min (using corn stover) and 86.9% at 190°C for 120 min (using wheat straw). In contrast, the digestion rates with 99.5% ethanol were 68.8 and 77.4% under the same conditions, respectively, indicating that there is a limit to the use of high-concentration ethanol as the solvent. To overcome this limitation, we applied a mechanical pretreatment step before the chemical pretreatment. Subsequently, glucose digestibility increased significantly to 93.1% with 99.5% ethanol as the solvent. Additionally the enzymatic digestibility of mechanically pretreated corn stover was higher than that of non-pretreated corn stover by about 40%. Taken together, these results confirm the efficacy of using high-concentration ethanol as a solvent for organosolv pretreatment when done in conjunction with mechanical pretreatment. [ABSTRACT FROM AUTHOR]

Experimental data obtained in studying processes that occur during the mechanoenzymatic hydrolysis of cell wall polymers of Saccharomyces cerevisiae yeast are presented. Special emphasis is placed on studying the reactivity of polymers contained in the supramolecular structure of cell walls, and on scaling the technology using pilot and industrial equipment. It is shown that mechanical treatment of yeast biomass allows us to alter the supramolecular structure of cell wall polymers and increase their reactivity in the enzymatic hydrolysis. Mechanical treatment disintegrates yeast cells and changes the supramolecular structure of polymers in their cell walls; the structural layers of a cell wall become disordered and diffused. A phenomenological model of mechanically activated enzymatic hydrolysis is proposed; the model is based on an autolocalization mechanism of the process. The domestic commercially available enzyme preparation CelloLux 2000 (OOO PA Sibbiopharm, Berdsk, Novosibirsk oblast) is used in this work. It is shown that changes in the supramolecular structure of yeast cell wall polymers occur during mechanically activated enzymatic hydrolysis. The yields of mannanoligosaccharides (1.1%) and mannanoproteins (2.7%) in the main extract are determined. Using pilot and industrial equipment at OOO PA Sibbiopharm, the technology is scaled and the production of a new mannanoligosaccharide product for animal husbandry is established. The pilot batch of the final product is effective against salmonellosis and is shown to increase the weight gain of experimental animals. [ABSTRACT FROM AUTHOR]

The effect of the mechanical activation of rice husk on the reactivity of its carbohydrates was studied. The activation was performed in a pilot-scale centrifugal roller mill. The mechanical treatment of the raw material led to an increase in its reactivity due to the increase in the specific surface area and amorphization of the crystalline regions of cellulose. The optimum process conditions of activation, leading to the preparation of a reactive product from rice husk, were determined: rotor frequency 1500 rpm, raw material feed rate 30 kg/h. The rice husk particles were ground to 45-50 μm under these conditions. These changes led to a sevenfold increase of the yield of low-molecular carbohydrates in the complete enzymatic hydrolysis of the material. [ABSTRACT FROM AUTHOR]

The aim of this study was to explore the efficiency of a mechano-enzymatic deconstruction of two macroalgae species for sugars and bioethanol production, by using a new enzymatic cocktail (Haliatase) and two types of milling modes (vibro-ball: VBM and centrifugal milling: CM). By increasing the enzymatic concentration from 3.4 to 30 g/L, the total sugars released after 72 h of hydrolysis increased (from 6.7 to 13.1 g/100 g TS and from 7.95 to 10.8 g/100 g TS for the green algae U. lactuca and the red algae G. sesquipedale, respectively). Conversely, total sugars released from G. sesquipedale increased (up to 126% and 129% after VBM and CM, respectively). The best bioethanol yield (6 geth/100 g TS) was reached after 72 h of fermentation of U. lactuca and no increase was obtained after centrifugal milling. The latter led to an enhancement of the ethanol yield of G. sesquipedale (from 2 to 4 g/100 g TS).