Saccharomyces cerevisiae spores are dormant cells, which can tolerate various types of environmental stress. In our previous work, we successfully developed biological and chemical methods for enzyme immobilization based on the structures of S. cerevisiae spore wall. In this study, we employed biological and chemical approaches for the immobilization of D-xylose isomerase (XI) from Thermus thermophilus and D-psicose 3-epimerase (DPEase) from Agrobacterium tumefaciens with yeast spores, respectively. The enzymatic properties of both immobilized XI and DPEase were characterized and the immobilized enzymes exhibit higher thermostability, broader pH tolerance, and good repeatability compared with free enzymes. Furthermore, we established a two-step approach for the bioconversion of D-glucose to D-psicose using immobilized enzymes. To improve the conversion yield, a multi-pot strategy was adopted for D-psicose production by repeating the two-step process continually. As a result, the yield of D-psicose was obviously improved and the highest yield reached about 12.0 %.

Maca ( Lepidium meyenii Walp.), originated in the high Andes of Peru, is rich in nutrients and phytochemicals. As a new resource food in China, Maca suffers marketing disorders due to the limitation of basic research. Due to the close relationship of Maca quality and origin of place, it’s of scientific, economic and social importance to set up a rapid, reliable and efficient method to identify Maca origin. In the present study, 303 Maca samples were collected from 101 villages of the main producing area in China. Using electronic nose and BP neutral network algorithm, a Maca odor database was set up to trace the origin. GC-MS was then employed to analyze the characteristic components qualitatively and semi-quantitatively. As a result, very significant differences ( p < 0.01) were detected in the volatile components of Maca from different areas. This study not only constructs a network model to forecast the Maca origin, but also reveals the relationship between Maca odor fingerprints and origins.

This study evaluated the stability of casein phosphopeptides (CPP) and obtained peptide–calcium complex by heating and chelating the peptide with CaCl2 in a neutral solution. To assess the bioavailability of various calcium formulations, the calcium transport models were established in Caco‐2 cells, and the transcellular transport pathways of various calcium formulations were studied by RT‐PCR and Western blotting. Results of circular dichroism showed that CPP was a stable polypeptide. The ultraviolet absorption spectrum and Fourier transform‐infrared spectrum (FT‐IR) indicated that calcium could be chelated by carboxyl oxygen and amino nitrogen atoms of CPP to form peptide calcium chelate, and the calcium bioavailability of peptide calcium chelate was significantly higher than that of CaCl2, calcium l‐aspartate, and casein phosphopeptides mixed with CaCl2. Four calcium sources increased the expression of TRPV5 and TRPV6 genes and proteins. The study intended to provide a basis for developing a novel calcium supplement. Practical applications This paper examined the bioavailability of casein phosphopeptides calcium complex, CaCl2, calcium l‐aspartate, and casein phosphopeptides mixed with CaCl2 in Caco‐2 cells, and the mechanisms were detected by western blotting. The results provide theoretical knowledge for the selection of calcium supplement raw materials and lay a foundation for the development of compound calcium preparations and drugs in the future.

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This work focused on the separation of the active ingredients of maca (Lepidium meyenii Walpers) and evaluated the antioxidative capability of these components with effects on improving glucose and lipid metabolism in insulin‐resistant HepG2 cells. DPPH free radical scavenging and reducing power assays were used to evaluate the antioxidant activity of maca extracts. An insulin‐resistant HepG2 cell model induced by glucose, fructose, oleic acid, and palmitic acid was adopted to investigate the effects of maca extracts on regulating glucose and lipid metabolism in this study. LC‐MS/MS was then used for determination of the maca n‐butanol (NBT) subfraction. The results showed that maca ethanol extract and subfractions of this extract exhibited certain antioxidant capacity. Furthermore, the NBT subfraction reversed the disorders in glucose and lipid metabolism in insulin‐resistant HepG2 cells and significantly increased the mRNA expression of phosphoinositide 3‐kinases (PI3K) and AKT in insulin‐resistant HepG2 cells in a dose‐dependent manner. In addition, the LC‐MS/MS results showed that the NBT subfraction contained many active ingredients. Overall, this study suggests that the NBT subfraction of the ethanol extract rich in glucosinolates modulates insulin resistance via PI3K/AKT activation in insulin‐resistant HepG2 cells and might exert potentially beneficial effects in improving or treating glucose and lipid metabolic disorders.

Our results suggest that, in quiescent cells, nutrient signals do not merely provoke a positive regulatory process to commence mitotic growth. Exit from the quiescent state in yeast cells is regulated by balancing between the positive and negative signaling pathways.

Intermittent fasting (IF) is a promising paradigm for weight loss which has been shown to modulate the gut microbiota based on 16S rRNA gene amplicon sequencing. Here, 72 Chinese volunteers with a wide range of body mass index (BMI) participated in a three-week IF program during which an average loss of 3.67 kg body weight accompanied with improved clinical parameters was observed irrespective of initial anthropometric and gut microbiota status. Fecal samples were collected before and after the intervention and subjected to shotgun metagenomic sequencing. De novo assembly yielded 2934 metagenome-assembled genomes (MAGs). Profiling revealed significant enrichment of Parabacteroides distasonis and Bacteroides thetaiotaomicron after the intervention, with inverse correlations between their relative abundances and parameters related to obesity and atherosclerotic cardiovascular diseases (ASCVD). MAGs enriched after the intervention showed high richness and diversity of carbohydrate-active enzymes, with an increased relative abundances of genes related to succinate production and glutamate fermentation.

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