Exploring core functional microbiota responsible for the production of volatile flavour during the traditional brewing of Wuyi Hong Qu glutinous rice wine.

The objective of this study was to explore the core functional microbiota for the production of volatile flavour during the traditional brewing of Wuyi Hong Qu glutinous rice wine, one of the most typical representatives of rice wine in China. Microbiological analysis based on high-throughput sequencing (HTS) technology demonstrated that bacteria of Lactobacillus, Bacillus, Leuconostoc, Lactococcus, Raoultella, Staphylococcus, Pediococcus, and Weissella, and fungi of Saccharomyces, Saccharomycopsis, Rhizopus, Monascus, Pichia, Wickerhamomyces, Candida, and Aspergillus were the predominant genera during the traditional fermentation process. Principal component analysis (PCA) based on the relative abundance showed that both of bacterial and fungal communities varied significantly in different fermentation phases. Some predominant microbial species or genera (including bacteria of Bacillus spp., Staphylococcus spp., Weissella spp., and P. acidilactici, and fungi of M. purpureus, R. oryzae, R. arrhizus var. arrhizus, and A. niger) were detected at the initial brewing stage, and their populations decreased as the fermentation progressed, while those of Lactobacillus, Gluconacetobacter, Leuconostoc, Pichia, Wickerhamomyces, and Saccharomyces increased to become the predominant genera at the final stage. A total of 79 volatile compounds were identified in traditional fermentation starters and during the traditional brewing process, mainly including esters, alcohols, acids, aldehydes, ketones, and phenols. Heatmaps and PCA also revealed the significant variances in the composition of volatile compounds among different samples. Furthermore, the potential correlations between microbiota succession and volatile flavour dynamics were explored through bidirectional orthogonal partial least squares (O2PLS) based correlation analysis. Three bacterial genera, namely, Gluconacetobacter, Lactobacillus, Lactococcus, and three fungal genera of Pichia, Wickerhamomyces, and Saccharomyces, were determined as the core functional microbiota for production of main volatile compounds in Wuyi Hong Qu glutinous rice wine. To conclude, information provided by this study is valuable to the development of effective strategies for the selection of beneficial bacterial and fungal strains to improve the quality of Wuyi Hong Qu glutinous rice wine.

[Discharge characteristic and spectrum measurement of a new type of single filament in a dielectric barrier discharge].

A new type of single filament was observed in a dielectric barrier discharge (DBD) system for the first time. It was formed with a larger discharge gap (d=3. 8 mm) and a smaller discharge area (S= 1 cm x 1 cm) in an air/argon gas mixture. Compared with the single filament observed by other experimental groups, the new type of single filament is composed of volume discharge (VD) and surface discharge (SD). In addition, the single filament has excellent discharge stability and sustainability. In order to study more about the discharge characteristic of the new type of single filament in a half-cycle of the applied voltage and the plasma state in different positions of the discharge column in the side view of the new type of single filament, both a high speed framing camera (HSFC) and a spectrograph were used in the experiment. The instantaneous images of end and side view of the new type of single filament were taken by the HSFC with different exposure time, and the discharge characteristic of the new type of single filament in a half-cycle of the applied voltage was compared with that of glow discharge. The spectral lines of Ar I 763. 26 nm (2P6-->1S5) and Ar I 772.13 nm (2P2-->IS3) in different positions of the discharge column of the new type of single filament were measured by using optical emission spectra, and chosen to estimate the corresponding electron excitation temperature by the relative intensity ratio method. It was found that the new type of single filament is composed of VD and SD, and SD produces a dendritic discharge around VD. The discharge characteristic of the new type of single filament in a half-cycle of the applied voltage is similar to that of glow discharge, and a funnel-shaped discharge emerges at the instantaneous cathode. The spectral line intensity and the corresponding electron excitation temperature all decrease with the distance away from the electrodes, indicating that the plasma state in different positions of the discharge column in the side view of the new type of single filament is different.

[Spectra line profile and vibrational temperature of dot and line discharge in a dielectric barrier discharge].

The emission spectrum line shift and vibrational temperature of dot and line discharges, which coexist in argon/air dielectric barrier discharge, were measured and compared. Emission spectral lines of ArI (2P2 --> 1S5) and the N2 second positive band system (C 3pi(u) --> B 3pi(g)) were used to measure the spectrum line shift and the vibrational temperature respectively. It was found that the spectrum line shift of the dot discharge channel is larger than that of the line discharge channel, indicating that the former has high electron density compared to the latter. While the vibrational temperature of the dot discharge channel is lower than that of the line discharge channel.

Hypoglycemic and hypolipidemic activities of Grifola frondosa polysaccharides and their relationships with the modulation of intestinal microflora in diabetic mice induced by high-fat diet and streptozotocin.

This study aimed to investigate the hypoglycemic and hypolipidemic activities of polysaccharides from Grifola frondosa (GFP) in diabetic mice induced by high-fat diet (HFD) and streptozotocin (STZ). Results showed that oral administration of GFP markedly reduced the serum levels of fasting blood glucose (FBG), oral glucose tolerance (OGT), cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C), and significantly decreased the hepatic levels of TC, TG and free fatty acids (FFA). Meanwhile, high-dose of GFP supplementation (900 mg/kg day) also showed powerful effects on moderating the composition of intestinal microflora in diabetic mice, especially altering the functionally relevant intestinal microbial phylotypes. Spearman's correlation network analysis revealed that key microbial phylotypes responding to GFP intervention were strongly correlated with the glucose and lipid metabolic disorders associated parameters. Moreover, GFP treatment regulated mRNA expression levels of the genes responsible for hepatic glucose and lipid metabolism. It is noteworthy that GFP treatment markedly increased mRNA expression of cholesterol 7α-hydroxylase (CYP7A1) and bile salt export pump (BSEP), suggesting an enhancement of bile acids (BAs) synthesis and excretion in liver. These findings demonstrated that GFP could prevent hyperglycemia and hyperlipidemia in diabetic mice by altering gut microbiota and regulating hepatic glycolipid metabolism related genes, and therefore could be used as potential functional food ingredients for the prevention or treatment of hyperglycemia and hyperlipidemia.

Polyunsaturated fatty acids from microalgae Spirulina platensis modulates lipid metabolism disorders and gut microbiota in high-fat diet rats.

Effects of Spirulina platensis 55% ethanol extract (SPL55) on lipid metabolism in high-fat diet-induced hyperlipidaemic rats were investigated. Ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry indicated that SPL55 was enriched with polyunsaturated fatty acids. Meanwhile, serum and liver lipid levels, including total triglyceride, total cholesterol, and low-density-lipoprotein cholesterol, were significantly decreased in hyperlipidaemic rats of SPL55. Analysis of tissue sections showed that SPL55 treatment could markedly inhibit hepatic lipid accumulation and steatosis. Moreover, SPL55 regulated the mRNA and protein expression levels of SREBP-1c, HMG-CoA, PEPCK, ACC, and AMPK genes involved in lipid metabolism. Furthermore, SPL55 led to decrease the abundances of Turicibacter, Clostridium_XlVa, and Romboutsia, which were positive correlation with lipid metabolism indicators, and has also enriched Alloprevotella, Prevotella, Porphyromonadaceae, and Barnesiella. These results provided evidence that SPL55 might be developed as a functional food to ameliorate lipid metabolic disorders and hyperlipidaemia.

Ethanol extract of Ganoderma lucidum ameliorates lipid metabolic disorders and modulates the gut microbiota composition in high-fat diet fed rats.

The objective of this study was to investigate the effects of ethanol extract of Ganoderma lucidum (GL95) on hyperlipidaemia and gut microbiota, and its regulation mechanism in Wistar rats fed on a high-fat diet (HFD). UPLC-QTOF MS indicated that GL95 was enriched with triterpenoids, especially ganoderic acids. The results of the animal experiment showed that oral administration of GL95 markedly alleviated the dyslipidemia through decreasing the levels of serum total triglyceride (TG), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), and inhibiting hepatic lipid accumulation and steatosis. Furthermore, GL95 supplementation altered the composition of gut microbiota, in particular modulating the relative abundance of functionally relevant enterotypes compared with the HFD group. The Spearman's correlation analysis revealed that Alistipes, Defluviitalea, Peptococcaceae and Alloprevotella were negatively correlated with serum and hepatic lipid profiles. Meanwhile, the GL95 treatment regulated the mRNA expression levels of the genes involved in lipid and cholesterol metabolism. The findings above illustrate that Ganoderma triterpenoids have the potential to ameliorate lipid metabolic disorders, in part through modulating specific gut microbiota and regulating the genes involved in lipid and cholesterol metabolism, suggesting Ganoderma triterpenoids as a potential novel functional food for the treatment or prevention of hyperlipidaemia.

Effect of Grifola frondosa 95% ethanol extract on lipid metabolism and gut microbiota composition in high-fat diet-fed rats.

This study aimed to investigate the effects of 95% ethanol extract of G. frondosa (GF95) on lipid metabolism and gut microbiota composition in high-fat diet (HFD) fed rats. UPLC/Q-TOF MS indicated that GF95 was enriched with flavones, fatty acids and so on. Meanwhile, we found that body weight, serum lipid or liver index (total cholesterol, triglyceride, and low density lipoprotein cholesterol) levels were significantly decreased in GF95-treated HFD-fed rats. Furthermore, GF95 treatment regulated mRNA expression levels involved in lipid metabolism. GF95 consumption significantly enhanced the excretion of bile acids in the cecum. Besides, in this study, a higher abundance of Butyricimonas genus was revealed in the GF95 group, which is highly related to the highest production of short-chain fatty acids in the caecum contents among the experimental groups. Interestingly, results from network analysis showed that Butyricimonas were negatively correlated with serum and liver lipid profiles.

The regulation mechanisms of soluble starch and glycerol for production of azaphilone pigments in Monascus purpureus FAFU618 as revealed by comparative proteomic and transcriptional analyses.

Monascus spp. have been used for thousands of years as a traditional food additive in China. This mold can produce many different types of commercially valuable secondary metabolites of biological activity. Soluble starch and glycerol are the two principal carbon sources universally utilized by Monascus for the production of beneficial metabolites. In this study, the effects and regulation mechanisms of soluble starch and glycerol for M. purpureus FAFU618 on Monascus azaphilone pigments (MonAzPs) were investigated through ultra-performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-QTOF-MS/MS), comparative proteomics and quantitative real-time reverse transcription polymerase chain reaction (RT-qPCR). The production of intracellular and extracellular pigments was significantly different between the soluble starch group (SSG) and glycerol group (GCG). Additionally, the components of intracellular pigments revealed by UPLC-QTOF-MS/MS showed that Monascin and Ankaflavin increased significantly in the GCG, while Rubropunctatin and Monascorubrin increased in the SSG. Differentially expressed proteins of mycelia between SSG and GCG were analyzed by two-dimensional gel electrophoresis (2-DE) and MALDI-TOF/TOF MS. We identified 27 proteins with statistically altered expression, of which 18 proteins associated with the EMP (glycolytic pathway), translation, energy generation, proteolysis, etc. were up-regulated, and 9 proteins, including ribosomal proteins, heat shock proteins (HSPs) and others, were down-regulated in GCG. Meanwhile, the expression levels of MonAzP biosynthetic genes were also analyzed by RT-qPCR, and the results showed that mppA, mppC, mppR1 and mppR2 were down-regulated, whereas genes MpPKS5, MpFasA2, MpFasB2, mppB, mppD and mppE were up-regulated. Collectively, these findings illustrate that the regulation of MonAzPs is not only closely related to the expression levels of certain proteins in the polyketide synthesis pathway but also closely related to the concentration of primary metabolism-generated molecules that are used as substrates for polyketide synthesis. The present study provides insights into the regulation of different carbon sources on the metabolism of MonAzPs in M. purpureus FAFU618. These results may promote further development of functional foods or medicines from Monascus spp. fermented products.