Exploration of the Product Specificity of chitosanase CsnMY002 and Mutants Using Molecular Dynamics Simulations

Chitosanase CsnMY002 is a new type of enzyme isolated from Bacillus subtilis that is used to prepare chitosan oligosaccharide. Although mutants G21R and G21K could increase Chitosan yield and thus increase the commercial value of the final product, the mechanism by which this happens is not known. Herein, we used molecular dynamics simulations to explore the conformational changes in CsnMY002 wild type and mutants when they bind substrates. The binding of substrate changed the conformation of protein, stretching and deforming the active and catalytic region. Additionally, the mutants caused different binding modes and catalysis, resulting in different degrees of polymerization of the final Chitooligosaccharide degradation product. Finally, Arg37, Ile145 ~ Gly148 and Trp204 are important catalytic residues of CsnMY002. Our study provides a basis for the engineering of chitosanases

Modulation of Gut Microbiota by Lactobacillus casei Fermented Raspberry Juice In Vitro and In Vivo

The aim of this study was to investigate the modulation of gut microbiota by fermented raspberry juice (FRJ) both in vitro and in vivo. Results showed that total phenolic content and antioxidant activities of FRJ reached the highest after fermentation for 42 h. Seventeen phenolic compounds were contained in FRJ, mainly including ellagic acid (496.64 ± 2.91 μg/g) and anthocyanins (total concentration: 387.93 μg/g). FRJ modulated the gut microbiota into a healthy in vitro status, with increase of valeric and isovaleric acids production. In healthy mice, all FRJ treatments improved the production of acetic, butyric and isovaleric acids as well as the gene expression of ZO-1, Claudin-1, Claudin-4, Ocdudin, E-cadherin and Muc-2. Moreover, variable gut microbial compositions were found among the groups fed diet-supplemented the different doses of FRJ, within low and median doses of FRJ may regulate the microbiota to a healthier state compared to the high dose supplementation. This study indicated that fermentation is a potential way to produce plant-based juices, which could reshape the gut microbiota and improve the host health

Semiconductor-Ionic Nanocomposite La0.1Sr0.9MnO3−δ-Ce0.8Sm0.2O2−δ Functional Layer for High Performance Low Temperature SOFC

A novel composite was synthesized by mixing La0.1Sr0.9MnO3−δ (LSM) with Ce0.8Sm0.2O2−δ (SDC) for the functional layer of low temperature solid oxide fuel cell (LT-SOFC). Though LSM, a highly electronic conducting semiconductor, was used in the functional layer, the fuel cell device could reach OCVs higher than 1.0 V without short-circuit problem. A typical diode or rectification effect was observed when an external electric force was supplied on the device under fuel cell atmosphere, which indicated the existence of a junction that prevented the device from short-circuit problem. The optimum ratio of LSM:SDC = 1:2 was found for the LT-SOFC to reach the highest power density of 742 mW·cm−2 under 550 °C The electrochemical impedance spectroscopy data highlighted that introducing LSM into SDC electrolyte layer not only decreased charge-transfer resistances from 0.66 Ω·cm2 for SDC to 0.47–0.49 Ω·cm2 for LSM-SDC composite, but also decreased the activation energy of ionic conduction from 0.55 to 0.20 eV

The effect of environmental heterogeneity on species richness depends on community position along the environmental gradient

Publisher's version/PDFEnvironmental heterogeneity is among the most important factors governing community structure. Besides the widespread evidence supporting positive relationships between richness and environmental heterogeneity, negative and unimodal relationships have also been reported. However, few studies have attempted to test the role of the heterogeneity on species richness after removing the confounding effect of resource availability or environmental severity. Here we constructed an individual-based spatially explicit model incorporating a long-recognized tradeoff between competitive ability and stress-tolerance ability of species. We explored the impact of the level of resource availability (i.e. the position of the community along a gradient of environmental severity) on the heterogeneity-diversity relationship (HDR). The results indicate that the shape of HDR depends on the community position along the environmental gradient: at either end of the gradient of environmental severity, a positive HDR occurred, whereas at the intermediate levels of the gradient, a unimodal HDR emerged. Our exploration demonstrates that resource availability/environmental severity should be considered as a potential factor influencing the shape of the HDR. Our theoretical predictions represent hypotheses in need of further empirical study.The work was financially supported by the National Natural Science Foundation of China (41201050, 31570426 and 31000199) and the Fundamental Research Funds for the Central Universities (lzujbky-2013-k15). CC also benefited from the Program for New Century Excellent Talents in University (NCET-12-0248). JTL was supported by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada