模拟肠液对Pen a1及其抗原表位免疫原性的影响

体外模拟人体肠液(SIF)消化分析Pen a1消化后免疫原性的变化规律。虾致敏蛋白Pen a1及其表位多肽经SIF消化后,用全抗体和表位特异性抗体检测Pen a1及其各抗原表位的免疫原性的变化,并测定表位多肽的SIF消化稳定性。结果表明,Pen a1的免疫原性在消化60 min内下降显著,在90 min后下降缓慢,生成的新片段仍具有免疫原性,但会逐步完全分解至SDS-PAGE无法检测出;Pen a1中5个抗原表位的免疫原性变化也类似。Western-blot表明五个表位抗体与生成的新蛋白结合程度不同,No.3、4、5抗体与20~30 ku处的新蛋白片段结合多于No.1、2。ELISA检测表明即使经过4 h的消化,免疫原性也只是降低了80%。Pen a1各表位消化稳定性为No.2No.1No.3No.4No.5;5个表位多肽的消化稳定性为No.3No.1No.4No.2No.5,与各表位上的酶切位点的个数呈负相关。可以得出Pen a1中No.2表位具有最高的消化稳定性,No.5表位表消化稳定性最差。     

Insights into the role of bacteria in vitamin A biosynthesis: Future research opportunities

Abstract

Significant efforts have been made to address the hidden hunger challenges due to iron, zinc, iodine, and vitamin A since the beginning of the 21st century. Prioritizing the vitamin A deficiency (VAD) disorders, many countries are looking for viable alternative strategies such as biofortification. One of the leading causes of VAD is the poor bioconversion of β-carotene into retinoids. This review is focused on the opportunities of bacterial biosynthesis of retinoids, in particular, through the gut microbiota. The proposed hypothesis starts with the premise that an animal can able to store and timely convert carotenoids into retinoids in the liver and intestinal tissues. This theory is experimental with many scientific insights. The syntrophic metabolism, potential crosstalk of bile acids, lipocalins and lipopolysaccharides of gut microbiota are reported to contribute significantly to the retinoid biosynthesis. The gut bacteria respond to these kinds of factors by genetic restructuring driven mainly by events like horizontal gene transfer. A phylogenetic analysis of β-carotene 15, 15′-mono (di) oxygenase enzymes among a selected group of prokaryotes and eukaryotes was carried out to validate the hypotheses. Shedding light on the probiotic strategies through non-genetically modified organism such as gut bacteria capable of synthesizing vitamin A would address the VAD disorders.     

猕猴桃果汁润肠通便保健功能的动物试验

对猕猴桃果汁润肠通便功能进行了动物试验研究。猕猴桃果汁在7d动物试验中，能明显促进便秘小鼠的小肠推进运动，缩短便秘小鼠的首次排便时间和增加其所排粪便量，提示猕猴桃果汁具有润肠通便功能，是一种当今较为理想的通便产品。     

In vitro batch fecal fermentation comparison of gas and short-chain fatty acid production using "slowly fermentable" dietary fibers

Abstract: Sustained colonic fermentation supplies beneficial fermentative by‐products to the distal colon, which is particularly prone to intestinal ailments. Blunted/delayed initial fermentation may also lead to less bloating. Previously, we reported that starch‐entrapped alginate‐based microspheres act as a slowly fermenting dietary fiber. This material was used in the present study to provide a benchmark to compare to other “slowly fermentable” fibers. Dietary fibers with previous reports of slow fermentation, namely, long‐chain inulin, psyllium, alkali‐soluble corn bran arabinoxylan, and long‐chain β‐glucan, as well as starch‐entrapped microspheres were subjected to in vitro upper gastrointestinal digestion and human fecal fermentation and measured over 48 h for pH, gas, and short‐chain fatty acids (SCFA). The resistant fraction of cooked and cooled potato starch was used as another form of fermentable starch and fructooligosaccharides (FOS) served as a fast fermenting control. Corn bran arabinoxylan and long‐chain β‐glucan initially appeared slower fermenting with comparatively low gas and SCFA production, but later fermented rapidly with little remaining in the final half of the fermentation period. Long‐chain inulin and psyllium had slow and moderate, but incomplete, fermentation. The resistant fraction of cooked and cooled potato starch fermented rapidly and appeared similar to FOS. In conclusion, compared to the benchmark slowly fermentable starch‐entrapped microspheres, a number of the purported slowly fermentable fibers fermented fairly rapidly overall and, of this group, only the starch‐entrapped microspheres appreciably fermented in the second half of the fermentation period. Practical Application: Consumption of dietary fibers, particularly commercial prebiotics, leads to uncomfortable feelings of bloating and flatulence due to their rapid degradation in our large intestine. This article employs claimed potential slowly fermenting fibers and compares their fermentation rates with a benchmark slow fermenting fiber that we fabricated in an in vitro simulation of the human digestive system. Results show a variety of fermentation profiles only some of which have slow and extended rate of fermentation.     

双歧杆菌活菌颗粒制剂对小鼠肠道菌群的调节作用

双歧杆菌是得到广泛公认的益生菌。它除了能合成多种维生素外,还能在人体肠道内形成一个生物学屏障,有效地抑制、阻止致病菌和条件致病菌在肠道中入侵和定植,从而调整与改善人体肠道中的微生态环境,达到调理肠胃,增强免疫功能,抑制肿瘤和延缓衰老的效果。由于益生菌的特殊生理作用,使国内外医学界纷纷尝试应用益生菌制作保健品。目前,国内对双歧杆菌的基础性研究和活菌制剂的开发都十分活跃,其生物制剂已应用于临床治疗。含双歧杆菌活菌的保健品也深受群众的喜爱。本文观察了保健食品“某双歧杆菌活菌颗粒剂”对小鼠胃肠道菌的调节作用,报告…     

果寡糖对肥育猪生长及肠道菌群等的影响

本试验研究了饲粮中添加果寡糖对"杜长加”肥育猪生长及肠道菌群和消化酶活性的影响.与对照组相比,肥育猪日粮中添加0.50%和0.75%果寡糖使日增重分别提高了9.67%(P＜0.01)和10.67%(P＜0.01),使料重比分别降低了8.19%(P＜0.01)和7.60%(P＜0.05);添加0.50%和0.75%果寡糖使结肠中双歧杆菌、乳酸杆菌数分别增加了299.49%(P＜0.01)和314.81%(P＜0.01),97.40%(P＜0.05)和141.67%(P＜0.05),并使结肠内容物pH值分别降低了0.50(P＜0.05)和0.90个单位(P＜0.01).添加果寡糖使结肠中大肠杆菌数、梭菌数下降,十二指肠内容物中总蛋白水解酶、胰蛋白酶、淀粉酶活性提高,果寡糖对胰脏中消化酶活性的影响不显著.     

Physiological relevance of food grade microcapsules: Impact of milk protein based microcapsules on inflammation in mouse models for inflammatory bowel diseases

In order to increase beneficial effects of bioactive compounds in functional food and dietary supplements, enormous efforts are put in the technological development of microcapsules. Although these products are often tailor‐made for disease susceptible consumer, the physiological impact of microcapsule uptake on the respective target consumer has never been addressed. The present study aimed to assess the relevance of this aspect by analyzing the impact of milk protein based microcapsules on experimental inflammatory bowel disease. Long‐term feeding of sodium caseinate or rennet gel microcapsules resulted in significant alterations in the intestinal microbiota of healthy mice. In TNFΔARE/wt mice, a model for chronic ileal inflammation, rennet gel microcapsules resulted in further increased splenomegaly, whereas ileal inflammation was unchanged. In IL10^?/? mice, a model for chronic colitis, both types of microcapsules induced a local increase of the intestinal inflammation. The present study is the first to demonstrate that, independent of their cargo, microcapsules have the potential to affect the intestinal microbiota and to exert unprecedented detrimental effects on disease‐susceptible individuals. In conclusion, the impact of microcapsule uptake on the respective target consumer groups should be thoroughly investigated in advance to their commercial use in functional food or dietary supplements.     

Changes of antibiotic resistance genes and gut microbiota after the ingestion of goat milk

Antibiotic resistance genes, as newly emerging contaminants, have become a serious challenge to public health through the food chain. The gut of humans and animals is an important reservoir for the development and dissemination of antibiotic resistance genes because of the great abundance and diversity of intestinal microbiota. In the present study, we evaluated the influence of goat milk on the diversity and abundance of antibiotic resistance genes and gut microbial communities, especially pathogenic bacteria. Male mice were used, 12 for each of the 2 groups: a control group that received sterile distilled water and a treated group that received goat milk, and gut microbiota and antibiotic resistance genes were compared in these groups using metagenomic analysis. The results revealed that ingestion of goat milk decreased the diversity and abundance of antibiotic resistance genes in the mice gut. The relative abundance of fluoroquinolone, peptide, macrolide, and β-lactam resistance genes in the total microbial genes significantly decreased after the intervention. Goat milk intake also significantly reduced the abundance of pathogenic bacteria, such as Clostridium bolteae, Clostridium symbiosum, Helicobacter cinaedi, and Helicobacter bilis. Therefore, goat milk intake might decrease the transfer potential of antibiotic resistance gene to pathogenic bacteria in the gut. In addition, bacteria with multiple resistance mechanisms accounted for approximately 4.5% of total microbial communities in the control group, whereas it was not detectable in the goat milk group, indicating the total inhibition by goat milk intake. This study highlights the influence of goat milk on antibiotic resistome and microbial communities in the gut, and provides a new insight into the function of goat milk for further study.     

豌豆超微粉碎膳食纤维对糖尿病小鼠肠道菌群及其代谢产物的影响

目的：研究豌豆超微粉碎膳食纤维（ultrafine ground pea dietary fiber,UGPDF）对糖尿病小鼠肠道菌群及其代谢产物的影响,从而揭示其降血糖的作用机制。方法：通过腹腔注射链脲佐菌素建立糖尿病小鼠模型,用二甲双胍和高剂量（0.9 g/（mL·d））、低剂量（0.45 g/（mL·d））UGPDF分别灌胃干预4 周,测定小鼠血糖浓度、观察肝脏细胞形态变化,Western blot检测小鼠肝脏中磷脂酰肌醇-3-激酶（phosphatidylinositol-3-kinase,PI3K）/蛋白激酶B（protein kinase B,AKT）/类胰岛素生长因子（insulin-like growth factors,IGF）蛋白表达水平,高通量测序分析各组小鼠粪便中的肠道菌群组成。结果：UGPDF能够调节糖尿病小鼠的肠道菌群丰度及多样性,高剂量UGPDF组操作分类单元（operational taxonomic units,OTU）数达300±36,其Shannon、Simpson指数与糖尿病小鼠存在显著差异（P＜0.05）。在肠道菌群组成中,与模型组相比,UGPDF干预后,Lactobacillus、Lachnospiraceae有益菌相对丰度显著上升（P＜0.05）,Helicobacter、Klebsiella、Clostridium致病菌相对丰度显著下降（P＜0.05）。从代谢产物来看,与模型组相比,经过UGPDF干预后,小鼠粪便内的6 种短链脂肪酸含量总体显著升高（P＜0.05）,其中以高剂量组效果最为显著,乙酸、丙酸、丁酸含量分别提高了63.7%、75.9%和96.0%,且接近正常对照组。同时,肝脏组织切片及Western blot检测结果表明UGPDF可调节糖尿病小鼠肝脏PI3K/AKT/IGF信号通路,修复肝细胞损伤,提高胰岛素敏感性。本实验可为豌豆膳食纤维的高值化利用拓宽思路,并补充完善其降血糖理论。