Study on Biological Pathway of Carbon Dioxide Methanation Based on Microbial Electrolysis Cell

Realization of CO_(2) resource utilization is the main development direction of CO_(2) reduction.The CO_(2) methana-tion technology based on microbial electrolysis cell(MEC)has the characteristics of ambient temperature and pressure,green and low-carbon,which meets the need of low-carbon energy transition.However,the lack of the system such as the change of applied voltage and the reactor amplification will affect the methane production efficiency.In this research,the efficiency of methane production with different applied voltages and different types of reactors was carried out.The results were concluded that the maximum methane production rate of the H-type two-chamber microbial electrolysis cells(MECs)at an applied voltage of 0.8 V was obtained to be 1.15 times higher than that of 0.5 V;under the same conditions of inoculated sludge,the reactor was amplified 2.5 times and the cumulative amount of methane production was 1.04 times higher than the original.This research can provide a theoretical basis and technical reference for the early industrial application of CO_(2) methanation tech-nology based on MEC.

Uniform stable conformal convolutional perfectly matched layer for enlarged cell technique conformal finite-difference time-domain method

Based on conformal construction of physical model in a three-dimensional Cartesian grid,an integral-based conformal convolutional perfectly matched layer（CPML） is given for solving the truncation problem of the open port when the enlarged cell technique conformal finite-difference time-domain（ECT-CFDTD） method is used to simulate the wave propagation inside a perfect electric conductor（PEC） waveguide.The algorithm has the same numerical stability as the ECT-CFDTD method.For the long-time propagation problems of an evanescent wave in a waveguide,several numerical simulations are performed to analyze the reflection error by sweeping the constitutive parameters of the integral-based conformal CPML.Our numerical results show that the integral-based conformal CPML can be used to efficiently truncate the open port of the waveguide.

Enhancing single-cell hyaluronic acid biosynthesis by microbial morphology engineering

Microbial morphology engineering is a novel approach for cell factory to improve the titer of target product in bio-manufacture.Hyaluronic acid(HA),a valuable glycosaminoglycan polymerized by HA synthase(HAS),a membrane protein,is particularly selected as the model product to improve its single-cell HA-producing capacity via morphology engineering.DivIVA and FtsZ,the cell-elongation and cell division related protein,respectively,were both down/up dual regulated in C.glutamicum via weak promoter substitution or plasmid overexpression.Different from the natural short-rod shape,varied morphologies of engineered cells,i.e.small-ellipsoid-like(DivIVA-reduced),bulb-like(DivIVA-enhanced),long-rod(FtsZ-reduced)and dumbbell-like(FtsZ-enhanced),were observed.Applying these morphology-changed cells as hosts for HA production,the reduced expression of both DivIVA and FtsZ seriously inhibited normal cell growth;meanwhile,overexpression of DivIVA didn't show morphology changes,but overexpression of FtsZ surprisingly change the cell-shape into long and thick rod with remarkably enlarged single-cell surface area(more than 5.2-fold-increase).And finally,the single-cell HA-producing capacity of the FtsZ-overexpressed C.glutamicum was immensely improved by 13.5-folds.Flow cytometry analyses verified that the single-cell HAS amount on membrane was enhanced by 2.1 folds.This work is pretty valuable for high titer synthesis of diverse metabolic products with microbial cell factory.