Escherichia coli expressing endoglucanase gene from Thai higher termite bacteria for enzymatic and microbial hydrolysis of cellulosic materials

Background: Endoglucanase plays a major role in initiating cellulose hydrolysis. Various wild-type strains were searched to produce this enzyme, but mostly low extracellular enzyme activities were obtained. To improve extracellular enzyme production for potential industrial applications, the endoglucanase gene of Bacillus subtilis M015, isolated from Thai higher termite, was expressed in a periplasmic-leaky Escherichia coli. Then, the crude recombinant endoglucanase (EglS) along with a commercial cellulase (Cel) was used for hydrolyzing celluloses and microbial hydrolysis using whole bacterial cells. Results: E. coli Glu5 expressing endoglucanase at high levels was successfully constructed. It produced EglS (55 kDa) with extracellular activity of 18.56 U/mg total protein at optimal hydrolytic conditions (pH 4.8 and 50\ub0C). EglS was highly stable (over 80% activity retained) at 40\u201350\ub0C after 100 h. The addition of EglS significantly improved the initial sugar production rates of Cel on the hydrolysis of carboxymethyl cellulose (CMC), microcrystalline cellulose, and corncob about 5.2-, 1.7-, and 4.0-folds, respectively, compared to those with Cel alone. E. coli Glu5 could secrete EglS with high activity in the presence of glucose (1% w/v) and Tween 80 (5% w/v) with low glucose consumption. Microbial hydrolysis of CMC using E. coli Glu5 yielded 26 mg reducing sugar/g CMC at pH 7.0 and 37\ub0C after 48 h. Conclusions: The recombinant endoglucanase activity improved by 17 times compared with that of the native strain and could greatly enhance the enzymatic hydrolysis of all studied celluloses when combined with a commercial cellulase

Optimization of Biodiesel Production from Waste Cooking Oil in a Continuous Mesoscale Oscillatory Baffled Reactor

In this study, a mesoscale oscillatory baffled reactor (OBR) was used to synthesize high methyl esters from waste cooking oil (WCO) in an alcoholic hydroxide solution. Preliminary experiments were conducted to screen for appropriate oscillating frequency and reaction temperature for the transesterification of WCO. Response surface methodology (RSM) based on the Box-Behnken design (BBD) was employed to investigate the influence of residence time, amount of catalyst and methanol-to-oil molar ratio on the fatty acid methyl ester (FAME) content of the product obtained from the OBR.  Based on the response surface approach, the optimum operating conditions for this process were as: a residence time of 60 s, a catalyst content of 3.0%, and a methanol-to-oil molar ratio of 11.  The physical and chemical properties of the product obtained were found to meet the standards

The Effect of Temperature on the Methanogenic Activity in Relation to Micronutrient Availability

In the view of microbial community, thermophilic microorganisms were reported to have faster biochemical reaction rates, which are reflected by a higher methane production rate. However, there has no research to discuss the effect of temperature on methanogenic activity in relation to micronutrient transport and availability. The objective of this study was to investigate the effect of temperature on methanogenic activity in relation to nutrient uptakes, micronutrient transports, and mass balance using anaerobic sequencing batch reactors (ASBR) with recycled biogas for treating ethanol wastewater at mesophilic (37 °C) and thermophilic (55 °C) temperatures. The increase in temperature from 37 to 55 °C increased in both of the optimum chemical oxygen demand (COD) loading rate and methanogenic activity, corresponding to the results of N and P uptakes, energy balance, and mass balance. The higher temperature of the thermophilic operation as compared to the mesophilic one caused a lower water solubility of the produced H2S, leading to lowering the reduction of divalent cation micronutrients. The thermophilic operation could prevent the deficit of micronutrients, thus causing a higher methanogenic activity, while the mesophilic operation still had the deficit of most micronutrients, leading to the lower activity

Hydrogen-Rich Syngas Production from Biogas Reforming by Gliding Arc Plasma- Catalyst Minireactor

This research aim was to investigate the production of H2-rich syngas from simulated biogas waste using a developed gliding arc plasma minireactor integrated with nickel-based catalysts. The effect of different catalyst types of NiO/Al2O3, NiO/MS 5A and NiO/ZSM-5 zeolite on overall system performance was investigated. Different support types significantly affected physical and chemical properties of prepared catalyst and had the dominant roles on the biogas plasma reforming in different ways. The integration of NiO/Al2O3 catalysts into gliding arc plasma minireactor gave the remarkable enhancement of H2 product in syngas with high H2 selectivity and H2/CO molar ratio of 63.59% and 2.91, respectively. Using NiO/Al2O3 catalyst in this plasma system lead the synergistic effect on H2 selectivity, as compared the only plasma system. NiO/ZSM-5 catalyst provided the highest CH4 conversion of 19.29% and also gave the minimum consumed energy of system (Ec=6.14x10-18 W·s/molecule of biogas converted and Es=5.52x10-18 W·s/molecule of syngas produced). The gliding arc plasma minireactor of this work performed the biogas reforming better than other low-temperature plasma such as conventional dielectric barrier discharge system

Kinetic Study on Microwave-Assisted Oligomerization of 1-Decene over a HY Catalyst

A promising production route for a high-quality base stock for lubricants is the oligomerization of high molecular-weight olefins in a high energy efficiency system. Oligomerization of 1-decene (C10) was conducted in a microwave-assisted system over a HY zeolite catalyst at different reaction temperatures and times. Higher reaction temperature resulted in increasing formation of dimers and trimers. The oligomerization reaction yielded 80% conversion, 54.2% dimer product, 22.3% trimer product and 3.4% heavier product at 483 K for a reaction time of 3 h. The best fit kinetic model for the dimerization reaction was formulated from an assumption of no vacant reaction sites. For the trimerization reaction, a molecule of dimer (C20) formed on the active site, interacted with a molecule of 1-decene in the bulk solution to form a molecule of trimer (C30). Apparent activation energies for the dimerization and trimerization reactions were 70.8 ± 0.8 and 83.6 ± 0.9 kJ/mol, respectively. The C13-NMR spectrum indicated that the oligomer product contained a significant portion of highly branched hydrocarbons, causing a substantial reduction in the viscosity index compared to conventional poly-alpha olefin lubricant (PAO)

Three-Stage Anaerobic Sequencing Batch Reactor (ASBR) for Maximum Methane Production: Effects of COD Loading Rate and Reactor Volumetric Ratio

A three-stage anaerobic sequencing batch reactor system was developed as a new anaerobic process with an emphasis on methane production from ethanol wastewater. The three-stage anaerobic sequencing batch reactor system consisted of three bioreactors connected in series. It was operated at 37 °C with a fixed recycle ratio of 1:1 (final effluent flow rate to feed flow rate) and the washout sludge from the third bioreactor present in the final effluent was allowed to be recycled to the first bioreactor. The pH of the first bioreactor was controlled at 5.5, while the pH values of the other two bioreactors were not controlled. Under the optimum chemical oxygen demand loading rate of 18 kg/m3d (based on the feed chemical oxygen demand load and total volume of the three bioreactors) with a bioreactor volumetric ratio of 5:5:20, the system provided the highest gas production performance in terms of yields of both hydrogen and methane and the highest overall chemical oxygen demand removal. Interestingly, the three-stage anaerobic sequencing batch reactor system gave a much higher energy production rate and a higher optimum chemical oxygen demand loading rate than previously reported anaerobic systems since it was able to maintain very high microbial concentrations in all bioreactors with very high values of both alkalinity and solution pH, especially in the third bioreactor, resulting in sufficient levels of micronutrients for anaerobic digestion