The Intervention of Prebiotics on Depression via the Gut-Brain Axis.

The imbalance of intestinal microbiota can cause the accumulation of endotoxin in the main circulation system of the human body, which has a great impact on human health. Increased work and life pressure have led to a rise in the number of people falling into depression, which has also reduced their quality of life. The gut-brain axis (GBA) is closely related to the pathological basis of depression, and intestinal microbiota can improve depressive symptoms through GBA. Previous studies have proven that prebiotics can modulate intestinal microbiota and thus participate in human health regulation. We reviewed the regulatory mechanism of intestinal microbiota on depression through GBA, and discussed the effects of prebiotics, including plant polysaccharides and polyphenols on the regulation of intestinal microbiota, providing new clues for the prevention and treatment of depression.

Green production of silybin and isosilybin by merging metabolic engineering approaches and enzymatic catalysis.

Silymarin extracted from milk thistle seeds, is used for treating hepatic diseases. Silybin and isosilybin are its main components, and synthesized from coupling of taxifolin and coniferyl alcohol. Here, the biosynthetic pathways of taxifolin and coniferyl alcohol were reconstructed in Saccharomyces cerevisiae for the first time. To alleviate substantial burden caused by a great deal of genetic manipulation, expression of the enzymes (e.g. ZWF1, TYR1 and ARO8) playing multiple roles in the relevant biosynthetic pathways was selectively optimized. The strain YT1035 overexpressing seven heterologous enzymes and five native enzymes and the strain YC1053 overexpressing seven heterologous enzymes and four native enzymes, respectively produce 336.8 mg/L taxifolin and 201.1 mg/L coniferyl alcohol. Silybin and isosilybin are synthesized from taxifolin and coniferyl alcohol under catalysis of APX1t (the truncated milk thistle peroxidase), with a yield of 62.5%. This study demonstrates an approach for producing silybin and isosilybin from glucose for the first time.

Correction: Gao et al. Research on Compressive Strength of Manufactured Sand Concrete Based on Response Surface Methodology. Materials 2024, 17, 195.

In the original publication [...].

Research on Compressive Strength of Manufactured Sand Concrete Based on Response Surface Methodology.

Due to the impact of economic and social development on the environment, there is an increasing demand for manufactured sand to replace natural sand as fine aggregate for concrete. At the same time, the effect of admixtures on the rheological properties and compressive strength of concrete is crucial in civil engineering applications. In this study, with the Box-Behnken test model, we analyzed and investigated the impact of a composite admixture of stone powder (SP), pulverized fuel ash (PFA), and silicon fume (SF) on the compressive strength of siliceous manufactured sand concrete using response surface methodology (RSM). At the same time, the rheological properties of the siliceous artificial sand and river sand concrete were analyzed. The prediction of the compressive strength of siliceous artificial sand concrete was developed using multiple regression analysis, the factors of which were SP, PFA, and SF content, and the response value was compressive strength. Furthermore, response surface and contour lines were used to analyze the impact of composite admixtures. It is shown that the compounding of SP, PFA, and SF improve the rheological properties of manufactured sand concrete. For the single factor, SP has the greatest effect on the compressive strength of mechanism sand concrete and SF has the least effect. For compounding, SP and PFA have the most significant effect on the compressive strength of artificial sand shotcrete, and the compounding of PFA and SF have the least effect.

Reconstruction of the Biosynthetic Pathway of Santalols under Control of the GAL Regulatory System in Yeast.

Sandalwood oil has been widely used in perfumery industries and aromatherapy. Santalols are its major components. Herein, we attempted to construct santalol-producing yeasts. To alter flux from predominant triterpenoid/steroid biosynthesis to sesquiterpenoid production, expression of ERG9 (encoding yeast squalene synthase) was depressed by replacing its innate promotor with PHXT1 and fermenting the resulting strains in galactose-rich media. And the genes related to santalol biosynthesis were overexpressed under control of GAL promotors, which linked santalol biosynthesis to GAL regulatory system. GAL4 (a transcriptional activator of GAL promotors) and PGM2 (a yeast phosphoglucomutase) were overexpressed to overall promote this artificial santalol biosynthetic pathway and enhance galactose uptake. 1.3 g/L santalols and 1.2 g/L Z-α-santalol were achieved in the strain WL17 expressing SaSS (α-santalene synthase from Santalum album) and WL19 expressing SanSyn (α-santalene synthase from Clausena lansium) by fed-batch fermentation, respectively. This study constructed the microbial santalol-producing platform for the first time.