Optimization of alkaline peroxide pretreatment of rice straw

Lignocellulose represents a promising starting material for conversion to fuels and chemicals in biorefinery; however, its efficient conversion to sugar requires a prerequisite pretreatment step. In the present research, the pretreatment of rice straw by alkaline peroxide pretreatment was studied aiming to enhance enzymatic digestibility of the cellulose-enriched solid. The alkaline hydrogen peroxide (AHP) pretreatment of rice straw using different concentration of hydrogen peroxide, reaction time, temperature, and solid loading were evaluated based on enzymatic digestibility and sugar recovery. The highest reducing sugar recovery was in the range of 499±6 mg/g native biomass after pretreatment using 2.5% H2O2 (v/v) at 35 ?C for 24 h and 7.5% biomass loading (w/v) after enzymatic hydrolysis using 20 FPU/g Accellerase® 1500. The work demonstrates the potential of the developed process for low temperature pretreatment of biomass for further conversion to value-added products.   Keywords: rice straw, biorefinery, alkaline peroxide pretreatmen

Study of Liquid Alkanes Production from Biomass-Derived Carbohydrates by Aldol-Condensation and Hydrogenation Processes

This research aims to synthesis liquid alkanes from biomass-derived hydroxyl methyl furfural (HMF) and furfural by aldol-condensation and hydrogenation processes over several catalysts i.e. TiO2, TiO2-ZrO2, Pd/Al2O3 and Pd/CeO2. It was found that the catalysts make significant impact on the selectivity and yield of alkanes product. It is noted that Pd/Al2O3 provided the highest alkane yield and selectivity. The aldol-condensation and hydrogenation of HMF over Pd/Al2O3 provide high C12 selectivity whereas the aldol-condensation and hydrogenation of furfural over Pd/Al2O3 provide high C8 selectivity. The effects of reaction temperature, reaction pressure and reaction time were then studied. The effect of inlet furfural to acetone molar ratio was also determined. It was also found that the optimized conditions to maximize the yield of alkane production from the aldol-condensation/hydrogenation of HMF and furfural are (i) at 53oC and 24 hr for aldol-condenstation of HMF, (ii) 80oC and 24 hr for aldol-condenstation of furfural, and (iii) 120oC for 6 hr with HMF to acetone molar ratio of 3:1 and furfural to acetone molar ratio of 4:1 in the presence of Pd/Al2O3 (calcined at 500oC) for hydrogenation reaction

Bioethanol Production from Glycerol by Mixed Culture System

AbstractGlycerol, a by-product from biodiesel industry, is a promising feedstock for subsequent bioconversion to higher-value products. Potential application of a mixed microbial consortium on the fermentative conversion of glycerol to ethanol was demonstrated in this study. Maximum ethanol concentration of 11.1 g l-1 was produced after 72 h fermentation from the initial pure glycerol concentration of 45 g l-1, at 30 ̊C, and pH 7 under anaerobic conditions, corresponding to the ethanol production rate and yield of 0.34 g l-1 h-1, and 0.81 mol ethanolmol-1 glycerol, respectively. The microbial consortium yielded lower ethanol concentration (6.5 g l-1) but similar ethanol yield (0.85 mol ethanol mol-1 glycerol) when crude glycerol of 45 g l-1 was fermented at the same condition. At the optimum fermentative condition of the pure glycerol, phylogenetic analysis of microbial consortium based on 16S rRNA gene sequences indicated that Gammaproteobacteria represented 95% of the microbial diversity in the consortium while the rest belonged to Betaproteobacteria. The consortium was dominated by bacteria closely related to genera Enterobacter and Klebsiella, which could play the role on conversion of glycerol to ethanol in this system

Hydrolysis of ionic liquid-treated substrate with an Iocasia fonsfrigidae strain SP3-1 endoglucanase.

Recently, we reported the discovery of a novel endoglucanase of the glycoside hydrolase family 12 (GH12), designated IfCelS12A, from the haloalkaliphilic anaerobic bacterium Iocasia fonsfrigidae strain SP3-1, which was isolated from a hypersaline pond in the Samut Sakhon province of Thailand (ca. 2017). IfCelS12A exhibits high substrate specificity on carboxymethyl cellulose and amorphous cellulose but low substrate specificity on b-1,3;1,4-glucan. Unlike some endoglucanases of the GH12 family, IfCelS12A does not exhibit hydrolytic activity on crystalline cellulose (i.e., Avicel™). High-Pressure Liquid Chromatography (HPLC) and Thin Layer Chromatography (TLC) analyses of products resulting from IfCelS12-mediated hydrolysis indicate mode of action for this enzyme. Notably, IfCelS12A preferentially hydrolyzes cellotetraoses, cellopentaoses, and cellohexaoses with negligible activity on cellobiose or cellotriose. Kinetic analysis with cellopentaose and barely b-D-glucan as cellulosic substrates were conducted. On cellopentaose, IfCelS12A demonstrates a 16-fold increase in activity (KM = 0.27 mM; kcat = 0.36 s-1; kcat/KM = 1.34 mM-1 s-1) compared to the enzymatic hydrolysis of barley b-D-glucan (KM: 0.04 mM, kcat: 0.51 s-1, kcat/KM = 0.08 mM-1 s-1). Moreover, IfCelS12A enzymatic efficacy is stable in hypersaline sodium chlorids (NaCl) solutions (up to 10% NaCl). Specifically, IfCel12A retains notable activity after 24 h at 2M NaCl (10% saline solution). IfCelS12A used as a cocktail component with other cellulolytic enzymes and in conjunction with mobile sequestration platform technology offers additional options for deconstruction of ionic liquid-pretreated cellulosic feedstock. KEY POINTS: • IfCelS12A from an anaerobic alkaliphile Iocasia fronsfrigidae shows salt tolerance • IfCelS12A in cocktails with other enzymes efficiently degrades cellulosic biomass • IfCelS12A used with mobile enzyme sequestration platforms enhances hydrolysis

Comparative analysis of bacterial communities associated with healthy and diseased corals in the Indonesian sea

Coral reef ecosystems are impacted by climate change and human activities, such as increasing coastal development, overfishing, sewage and other pollutant discharge, and consequent eutrophication, which triggers increasing incidents of diseases and deterioration of corals worldwide. In this study, bacterial communities associated with four species of corals: Acropora aspera, Acropora formosa, Cyphastrea sp., and Isopora sp. in the healthy and disease stages with different diseases were compared using tagged 16S rRNA sequencing. In total, 59 bacterial phyla, 190 orders, and 307 genera were assigned in coral metagenomes where Proteobacteria and Firmicutes were predominated followed by Bacteroidetes together with Actinobacteria, Fusobacteria, and Lentisphaerae as minor taxa. Principal Coordinates Analysis (PCoA) showed separated clustering of bacterial diversity in healthy and infected groups for individual coral species. Fusibacter was found as the major bacterial genus across all corals. The lower number of Fusibacter was found in A. aspera infected with white band disease and Isopora sp. with white plaque disease, but marked increases of Vibrio and Acrobacter, respectively, were observed. This was in contrast to A. formosa infected by a black band and Cyphastrea sp. infected by yellow blotch diseases which showed an increasing abundance of Fusibacter but a decrease in WH1-8 bacteria. Overall, infection was shown to result in disturbance in the complexity and structure of the associated bacterial microbiomes which can be relevant to the pathogenicity of the microbes associated with infected corals

Analysis of alkene monooxygenase from Xanthobacter strain Py2 : heterologous expression and investigation of coupling protein function

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Comparative study on liquefaction behaviors of xylan hemicellulose as treated by different hydrothermal methods

Liquefaction behaviors of xylan were studied as treated by six different hydrothermal methods. As a comparative study, a xylan sample isolated from corn core was subjected to hot-compressed water, hot-compressed 0.01 and 0.1wt% HO2 solutions under pressurization of N or CO2 at 110-250 °C for 0 min in 10-ml batch-type reactor. Not only xylose and xylo-oligosaccharides, but also arabinose, glucose, and acetic acid were recovered as hydrolyzed products. In addition, decomposition compounds, i.e. furans and organic acids were found. The highest xylose yield could be attained at 210 °C in all the studied hydrothermal methods, except for only 0.1wt% HO2 solution under pressurization of CO2. By this strongly oxidative condition, where peroxy carbonic acid was formed in situ, the temperature that xylose could be highly recovered was at 190 °C. The highest xylose yield of 61.62wt% was obtained by 0.01wt% HO2 solution under pressurization of N. Formation of furan compounds showed a preference to the treatments with pressurized CO2, while organic acids had a better recovery when N was applied. Different results in the production of various liquefied products could be attributed to the degree of hydrolysis and oxidation reactions which altered under the different hydrothermal methods