Xiang Fang

Comparative diversity analysis of gut microbiota in two different human flora-associated mouse strains.

The Kunming (KM) mouse is a closed colony mouse strain widely used in Chinese pharmacology, toxicology, and microbiology research laboratories. However, few studies have examined human flora-associated (HFA) microbial communities in KM mice. In this study, HFA models were built from germ-free KM and C57BL/6J mouse strains, and gut microbial diversity was analyzed by denaturing gradient gel electrophoresis (DGGE) and DNA sequencing. We found that the two strains of HFA mice were significantly different based on the UPGMA dendrogram and the Richness index, but dice similarity coefficients of mouse replicates were not significantly different between HFA-KM and HFA-C57BL/6J. Most of the dominant phyla of human gut microflora could be transferred into the guts of the two mouse strains. However, the predominant genus that formed in HFA-KM was Clostridium sp. and that in HFA-C57BL/6J was Blautia sp. These results imply that genotypes difference between the two mice strains is a critical factor in shaping the intestinal microflora. However, genetic differences of individuals within KM mouse populations failed to lead to individual difference in microflora. Successful generation of HFA-KM mice will facilitate studies examining how diet affects gut microbial structure, and will enable comparative studies for uncovering genetic factors that shape gut microbial communities.

Green Tea Polyphenols Modulate Colonic Microbiota Diversity and Lipid Metabolism in High‐Fat Diet Treated HFA Mice

There is an increasing interest in the effect of dietary polyphenols on the intestinal microbiota and the possible associations between this effect and the development of obesity. However, limited information is available on how these polyphenols affect the gut microbiota and lipid metabolism. The co-action of a high-fat diet (HFD) and tea polyphenol (TP) on gut microbiota and lipid metabolism using a human flora-associated (HFA) C57BL/6J mice model is studied. TP reduced serum total cholesterol, triglyceride, low density lipoprotein, glucose (GLU) and insulin (INS) levels of HFD mice in a dose-dependent manner (P < 0.01). TP also significantly increased acetic acid and butyric acid levels in HFA mice. 16S rRNA V3 region Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) profiles showed that HFD mice had significantly reduced microbial diversity. This reduction could be alleviated by TP, with a significant increase in the richness and diversity of colonic microbiota in the high-fat diet with 0.2% TP (TPM) and high-fat diet with 0.05% TP (TPL) groups (P < 0.05). 454 pyrosequencing analysis showed that the HFD group had a significant increase in the Bacteroidetes to Firmicutes (F/B) ratio (P < 0.001), which could effectively be reversed by TP. The results showed that the changes in composition and diversity of colonic microbiota by TP administration suppressed the host body weight and blood lipid increase in high-fat diet HFA mice.nnnPRACTICAL APPLICATIONnA high fat diet significantly impacted gut microbiota composition and lipid metabolism in human flora-associated mice, which were largely ameliorated by tea polyphenol (TP). Therefore, TPs may be effectively used in controlling or treating obesity, hyperlipidemia and other related metabolic diseases.

Impact of the Consumption of Tea Polyphenols on Early Atherosclerotic Lesion Formation and Intestinal Bifidobacteria in High-Fat-Fed ApoE−/− Mice

There is an increasing interest in the effect of dietary polyphenols on the intestinal microbiota and the possible associations between this effect and the development of some cardiovascular diseases, such as atherosclerosis (AS). However, limited information is available on how these polyphenols affect the gut microbiota and AS development. This study was designed to evaluate the modulation of dietary tea polyphenols (TPs) on intestinal Bifidobacteria (IB) and its correlation with AS development in apolipoprotein E-deficient (ApoE−/−) mice. Fifty C57BL/6 ApoE−/− mice were randomized into one of the five treatment groups (nu2009=u200910/group): control group fed normal diet (CK); a group fed a high-fat diet (HFD); and the other three groups fed the same HFD supplemented with TPs in drinking water for 16u2009weeks. The total cholesterol and low-density lipoprotein cholesterol (LDL-C) were decreased significantly (Pu2009<u20090.05) after TP interference. In addition, the TP diet also decreased the plaque area/lumen area (PA/LA) ratios (Pu2009<u20090.01) in the TP diet group. Interestingly, copies of IB in the gut of ApoE−/− mice were notably increased with TP interference. This increase was dose dependent (Pu2009<u20090.01) and negatively correlated with the PA/LA ratio (Pu2009<u20090.05). We conclude that TPs could promote the proliferation of the IB, which is partially responsible for the reduction of AS plaque induced by HFD.

The effect of green tea polyphenols on gut microbial diversity and fat deposition in C57BL/6J HFA mice

Quantitative and qualitative changes in gut microbial composition have been linked to obesity and obesity-related complications, and eating pattern has been shown to significantly impact the gut microbiome. Meanwhile, tea polyphenols are known to have health benefits such as improving glucose tolerance and decreasing liver fat deposition that may be helpful in combating obesity and obesity-related disorders. We therefore studied the effect of green tea polyphenols on gut microbial diversity and fat deposition in C57BL/6J Human Flora-Associated (HFA) mice, which were divided into five groups: low fat (LF), high fat (HF), high fat + 0.05% tea polyphenols (HF + 0.05% TP), high fat + 0.2% tea polyphenols (HF + 0.2% TP) and high fat + 0.8% tea polyphenols (HF + 0.8% TP). 16S rRNA V6-V8 region PCR-DGGE profiles showed that a high fat diet was associated with a significant reduction in microbial diversity. This reduction could be alleviated by a HF + 0.2% TP diet, with a significant increase in the number of lactic acid bacteria in the HF + 0.2% TP group compared with the LF group (P < 0.05). Body weight (P < 0.05) and fat pad weight (P < 0.001) were significantly increased in the HF compared with the LF group, with notable adipocyte hypertrophy in the HF group, indicating successful establishment of the high fat model. Body weight among the HF + 0.2% TP group and HF + 0.8% TP group (but not the HF + 0.05% TP group) was significantly lower than the body weight in the HF group (P < 0.01). Therefore, tea polyphenols may effectively retard diet-induced weight gain and body fat gain, adipocyte hypertrophy and hepatic steatosis in a dose-dependent manner.

Comparison of Bacterial Diversity Between Two Traditional Starters and the Round-Koji-Maker Starter for Traditional Cantonese Chi-Flavor Liquor Brewing

Xiaoqu is a traditional fermentation starter that is used for Chinese liquor production. Although microorganisms in the starters are closely associated with the quality and flavor of liquor, knowledge of the microbiota in xiaoqu is still far from complete, let alone the starters produced by new processes. Here, Illumina MiSeq high-throughput sequencing was applied to study bacterial composition in three types of xiaoqu used in Cantonese soybean-flavor (Chi-flavor) liquor, namely two traditional starters (Jiu Bing and Bing Wan) and a Round-Koji-maker starter (San qu) produced by the automatic starter-making disk machine. The results showed bacterial diversity in traditional starters was similar and higher than that in the Round-Koji-maker starter. Lactobacillus and Pediococcus were the dominant genera in all starters, while other different dominant genera also existed in different starters, which were Weissella, Acetobacter, and Gluconobacter for Jiu Bing, Weissella for Bing Wan, and Bacillus, Acetobacter, Acinetobacter and Klebsiella for San qu, respectively. Meanwhile, Cytophagaceae, one particular microbial family, and some pathogens including Klebsiella, Cronobacter, and Enterobacter were also found in San qu, indicating the automatic starter-making disk machine should be ameliorated before applied into industrial production. These results enriched our knowledge on xiaoqu-related microorganisms and might be helpful in industrial Chi-flavor liquor production and the development of fermentation technology.

Roles of Three HSF Domain-Containing Proteins in Mediating Heat-Shock Protein Genes and Sustaining Asexual Cycle, Stress Tolerance, and Virulence in Beauveria bassiana

Heat-shock transcription factors (HSFs) with a HSF domain are regulators of fungal heat-shock protein (HSP) genes and many others vectoring heat-shock elements, to which the domain binds in response to heat shock and other stress cues. The fungal insect pathogen Beauveria bassiana harbors three HSF domain-containing orthologous to Hsf1, Sfl1, and Skn7 in many fungi. Here, we show that the three proteins are interrelated at transcription level, play overlapping or opposite roles in activating different families of 28 HSP genes and mediate differential expression of some genes required for asexual developmental and intracellular Na+ homeostasis. Expression levels of skn7 and sfl1 largely increased in Δhsf1, which is evidently lethal in some other fungi. Hsf1 was distinct from Sfl1 and Skn7 in activating most HSP genes under normal and heat-shocked conditions. Sfl1 and Skn7 played overlapping roles in activating more than half of the HSP genes under heat shock. Each protein also activated a few HSP genes not targeted by two others under certain conditions. Deletion of sfl1 resulted in most severe growth defects on rich medium and several minimal media at optimal 25°C while such growth defects were less severe in Δhsf1 and minor in Δskn7. Conidiation level was lowered by 76% in Δskn7, 62% in Δsfl1, and 39% in Δhsf1. These deletion mutants also showed differential changes in cell wall integrity, antioxidant activity, virulence and cellular tolerance to osmotic salt, heat shock, and UV-B irradiation. These results provide a global insight into vital roles of Hsf1, Sfl1, and Skn7 in B. bassiana adaptation to environment and host.

Antibacterial activity of food-grade chitosan against Vibrio parahaemolyticus biofilms

Biofilm is a community composed of microbes and the extracellular polymeric substances. This special architecture poses a significant public health risk as it increases the fitness of bacteria in harsh conditions and renders bacterial resistance to antimicrobial agents and cleaning. In this study, we investigated the inhibition and eradication effects of chitosan on the biofilm of Vibrio parahaemolyticus, an important food-borne pathogen. The crystal violet staining, [2, 3-bis (2-methoxy-4-nitro-5- sulfophenyl)-2H-tetrazolium-5-carboxanilide] (XTT) reduction method, phenol-sulfuric acid method, fluorescence microscope and confocal laser scanning microscope (CLSM) observation were conducted. The results indicated that the minimum inhibitory concentration (MIC) of chitosan was 1.25xa0mg/mL. Sub-MIC of chitosan could significantly inhibit biofilm formation, reduce the metabolic activities and the secretion of extracellular polysaccharide (EPS). Moreover, chitosan at 4MIC could eradicate 85.06% mature biofilm of V.xa0parahaemolyticus, and decrease 81.43% EPS in mature biofilm. These results were also confirmed by the visual images obtained from fluorescence microscopy and CLSM. This study elucidated that chitosan was not only effective to prevent biofilm formation, but also eradicate mature biofilms of V.xa0parahaemolyticus.