In vitro digestion and fecal fermentation behaviors of exopolysaccharide from Morchella esculenta and its impacts on hypoglycemic activity via PI3K/Akt signaling and gut microbiota modulation.

This study aimed to evaluate the effects of gastrointestinal digestion on the physicochemical properties and hypoglycemic activity of extracellular polysaccharides from Morchella esculenta (MEPS). The results showed that the MEPS digestibility was 22.57 % after saliva-gastrointestinal digestion and only partial degradation had occurred. Contrarily, after 48 h of fecal fermentation, its molecular weight and molar ratios of the monosaccharide composition varied significantly due to being utilized by human gut microbiota, and the final fermentation rate was 76.89 %. Furthermore, the MEPS-I, the final product of saliva-gastrointestinal digestion still retained significant hypoglycemic activity, it alleviated insulin resistance and increased the IR cells glucose consumption by activating PI3K/AKT signaling pathway. MEPS-I treatment reduced the proportion of Firmicutes to Bacteroidetes, and the relative abundance of beneficial bacteria that enhanced insulin sensitivity and glucose uptake was promoted. This research can provide a theoretical basis for the further development of Morchella esculenta as a health functional food.

Comparative study on physicochemical properties and hypoglycemic activities of intracellular and extracellular polysaccharides from submerged fermentation of Morchella esculenta.

The structural characteristic, physicochemical properties and structure-hypoglycemic activity relationship of intracellular (IPS) and extracellular (EPS) from submerged fermentation of Morchella esculenta were systematically compared and assessed. Both IPS and EPS were neutral, with a triple-helical conformation, and composed of galactose, glucose and mannose monosaccharides in different molar ratios. The molecular weight and particle size of IPS were higher than those of EPS. FTIR and SEM showed that the main functional group absorption peak intensity, glycosidic bond type and surface morphology of the two polysaccharides differed. Analysis of rheological and thermal properties revealed that the viscosity of IPS was higher than that of EPS, while thermal stability of EPS was greater than that of IPS. Hypoglycemic activity analysis in vitro showed that both IPS and EPS were non-competitive inhibitors of α-amylase and α-glucosidase. EPS showed strong digestive enzyme inhibitory activity due to its higher sulphate content and molar ratio of galactose, lower Mw and particle size. Meanwhile, with its higher Mw and apparent viscosity, IPS showed stronger glucose adsorption capacity and glucose diffusion retardation. These results indicate that IPS and EPS differed considerably in structure and physicochemical properties, which ultimately led to differences in hypoglycemic activity. These results not only suggested that IPS and EPS has the potential to be functional foods or hypoglycemic drugs, but also provided a new target for the prevention and treatment of diabetes with natural polysaccharides.

Population Genetic Assessment Model Reveals Conservation Priorities for Gymnocypris Species Resources on the Qinghai-Tibetan Plateau.

The Qinghai-Tibetan Plateau (QTP) has nurtured a rich diversity of species because of its unique geographical and environmental conditions. Gymnocypris species (subfamily Schizopygopsinae) are primitive fishes that live in the special environment of the plateau, and their evolution and distribution are inseparable from the historical changes of the QTP. Recently, the resources of Gymnocypris species have been decreasing due to habit deterioration and the intensification of human activities. Therefore, the scientific conservation of the genetic resources of Gymnocypris species is urgently required. In this study, we established two models for the priority conservation assessment of germplasm resources of Gymnocypris species on the basis of the genetic diversity and phylogenetic relationships of 674 individuals from eight Gymnocypris species populations. The results show that the Gymnocypris potanini (GPO), Gymnocypris eckloni (GE), and Gymnocypris przewalskii (GPR) populations are the most genetically diverse in terms of combined genetic diversity values and should be prioritized for conservation. In terms of genetic contribution, the GPO, GE, and GPR populations have a positive impact on maintaining the distinctiveness and diversity of the entire Gymnocypris species population and should be prioritized for conservation. However, in terms of different evolutionary clades, the Gymnocypris namensis, Gymnocypris waddellii, Gymnocypris dobula, and GE populations in clade A should be given priority for protection, the GE population in clade B should be given priority, and the GPR population in clade C should be given priority. In conclusion, the two models and assessment of conservation priorities will provide a scientific basis for the conservation of Gymnocypris species.

Effect of Ultrasonic Treatment on the Physicochemical Properties of Bovine Plasma Protein-Carboxymethyl Cellulose Composite Gel.

In order to improve the stability of bovine plasma protein-carboxymethyl cellulose composite gels and to expand the utilization of animal by-product resources, this study investigated the impact of different ultrasound powers (300, 400, 500, 600, and 700 W) and ultrasound times (0, 10, 20, 30, and 40 min) on the functional properties, secondary structure and intermolecular forces of bovine plasma protein-carboxymethyl cellulose composite gel. The results showed that moderate ultrasonication resulted in the enhancement of gel strength, water holding capacity and thermal stability of the composite gels, the disruption of hydrogen bonding and hydrophobic interactions between gel molecules, the alteration and unfolding of the internal structure of the gels, and the stabilization of the dispersion state by electrostatic repulsive forces between the protein particles. The content of α-helices, ß-turns, and ß-sheets increased and the content of random curls decreased after sonication (p < 0.05). In summary, appropriate ultrasound power and time can significantly improve the functional and structural properties of composite gels. It was found that controlling the thermal aggregation behavior of composite gels by adjusting the ultrasonic power and time is an effective strategy to enable the optimization of composite gel texture and water retention properties.

Microbial succession and its correlation with the dynamics of flavor compounds involved in the fermentation of Longxi bacon.

Introduction: Longxi bacon is a traditional fermented meat from Gansu province, China. The ripening process of the bacon is crucial for quality and flavor. The aim of this study was to gain deeper knowledges on the bacterial and fungal community diversity and the changes of chemical components including fatty acids and volatile compounds at different time points during the ripening of the bacon and to understand the relationship between microbial profiles and the chemical components related the bacon flavor. Methods: Bacon samples were collected from days 0, 15, 30, 60 and 90. The bacterial and fungal compositions were analyzed with next generation sequencing targeting the 16S rDNA loci for bacteria and ITS loci for fungi. The fatty acids and the volatile components were analyzed by headspace solid phase micro extraction followed by gas chromatography/mass spectrometry (HS-SPME-GC/MS). Results: We found that the abundance of bacteria in bacon was higher than that of fungi, and Psychrobacter, Brochothrix, Phoma and Trichoderma was the dominant bacon's population. The largest contributors of volatiles were aldehydes, ketones and esters, and the main fatty acids were palmitic, oleic and linoleic acids. Pearson correlation analysis between microbial succession and key flavor substances showed that the production of Longxi bacon flavor is the result of a combination of bacteria and fungi. Ten bacteria genera and six fungi genera were determined as functional core microbiota for the flavor production based their dominance and functionality in microbial community. In addition, bacteria and fungi are involved in the oxidation and hydrolysis of fatty acids during the ripening of bacon, which also contributes to the formation of bacon flavor. Discussion: This study provides a comprehensive analysis of the key microbiota involved in shaping bacon's distinctive flavor. Here, the results presented should provide insight into the influence of the microenvironment on the microbial community in bacon and lay a foundation for further investigations into the food ecology of bacon.

SPOCK1 silencing decreases 5-FU resistance through PRRX1 in colorectal cancer.

SPOCK1 is an extracellular proteoglycan and involved in tumor growth and metastasis in various cancers. 5-fluorouracil (5-FU) is commonly used for the treatment of colorectal cancer (CRC) in patients who receive concurrent chemoradiotherapy. However, the relationship between development of resistance to 5-FU and SPOCK1 remain unclear. In this study, we established two 5-fluorouracil (5-FU)-resistant CRC cell lines, HCT116/FU and LOVO/FU, and found that SPOCK1 is upregulated in 5-FU-resistance CRC cells compared with its parental cell line. knockdown of SPOCK1 in 5-FU-resistant CRC cells increases their sensitivity to 5-FU. In contrast, transient transfection of SPOCK1 enhanced HCT116 and LOVO cell resistance to 5-FU and reduced cell apoptosis. Mechanistically, SPOCK1 promoted 5-FU resistance by regulating PRRX1 expression and the downstream apoptosis signaling pathway. Taken together, our results revealed for the first time that SPOCK1 plays a crucial role in the resistance of CRC cells to 5-FU and indicated that targeting SPOCK1 may be a promising therapeutic strategy to overcome 5-FU resistance in CRC.

Manipulation of the Regulatory Genes ppsR and prrA in Rhodobacter sphaeroides Enhances Lycopene Production.

Rhodobacter sphaeroides is a non-sulfur purple bacterium with great metabolic versatility, capable of producing a variety of valuable compounds that include carotenoids and CoQ10. In order to enhance lycopene production, we deleted the photosynthetic gene cluster repressor ppsR from a lycopene-producing Rb. sphaeroides strain (RL1) constructed in a previous study to break the control of carotenoid synthesis by the oxygen level. Also, lycopene production was further increased by overexpression of the activator prrA. The superior lycopene producer DppsR/OprrA thus obtained had a high growth rate and a lycopene production of 150.15 mg/L with a yield of 21.45 mg/g dry cell weight (DCW) under high oxygen conditions; these values were ≥6.85-fold higher than those of RL1 (19.13 mg/L; 3.32 mg/g DCW). Our findings indicate that elimination of oxygen repression led to more efficient lycopene production by DppsR/OprrA and that its increased productivity under high oxygen conditions makes it a potentially useful strain for industrial-scale lycopene production.

Calcium regulates glutamate dehydrogenase and poly-γ-glutamic acid synthesis in Bacillus natto.

OBJECTIVE: To study the effect of Ca(2+) on glutamate dehydrogenase (GDH) and its role in poly-γ-glutamic acid (γ-PGA) synthesis in Bacillus natto HSF 1410. RESULTS: When the concentration of Ca(2+) varied from 0 to 0.1 g/l in the growth medium of B. natto HSF 1410, γ-PGA production increased from 6.8 to 9.7 g/l, while GDH specific activity and NH4Cl consumption improved from 183 to 295 U/mg and from 0.65 to 0.77 g/l, respectively. GDH with α-ketoglutarate as substrate primarily used NADPH as coenzyme with a K m of 0.08 mM. GDH was responsible for the synthesis of endogenous glutamate. The specific activity of GDH remained essentially unchanged in the presence of CaCl2 (0.05-0.2 g/l) in vitro. However, the specific activity of GDH and its expression was significantly increased by CaCl2 in vivo. Therefore, the regulation of GDH and PGA synthesis by Ca(2+) is an intracellular process. CONCLUSION: Calcium regulation may be an effective approach for producing γ-PGA on an industrial scale.