益生菌抑制致病菌作用的机制研究进展

致病菌引起的各种胃肠道疾病对人类健康造成危害,应用益生菌制剂防治致病菌感染,具有安全和减少耐药性等优点,为控制致病菌感染性疾病提供了新的途径。主要从益生菌与致病菌竞争黏附位点、与致病菌的共聚作用及其产生的抗菌物质三个方面综述益生菌抑制致病菌的作用机制。     

益生菌的作用机理及功能的研究进展

益生菌是一种改善肠道菌群平衡的微生物饲料添加剂。本文主要探讨它具有改善肠道功能、增强免疫力、抗高血压,调控泌尿系统健康等功能。从益生菌与致病菌竞争黏附位点、抗菌效应,提高免疫力及其提高消化吸收四个方面综述益生菌抑制致病菌的作用机理。     

益生菌黏附能力评估模型的研究进展

益生菌的黏附能力是益生菌在宿主肠道中稳定定殖的关键,也是益生菌发挥作用的前提。研究者常以益生菌的黏附能力作为筛选益生菌菌种的重要标准,因此建立稳定的益生菌黏附能力评估模型一直是该领域的研究热点。着重介绍了益生菌黏附能力评估模型的种类和检测方法,旨在为益生菌黏附能力评估模型的研究及应用提供参考。     

转基因益生菌：预防肠道感染的新型微生态制剂

引起主要肠道疾病的许多致病菌能够特异性地利用宿主肠道细胞表面的各式寡糖, 将其作为自身黏附或者分泌毒素的受体。因此, 阻断致病菌及其分泌毒素与宿主靶细胞表面受体结合是一种可行的治疗方法。一类宿主肠道细胞表面受体基因重组益生菌在消化道内能够高效结合致病菌和所分泌的毒素, 具有良好的预防肠道疾病的应用前景。本文主要以类志贺毒素受体重组益生菌为例, 阐述转基因益生素的原理、技术及其疗效和潜在的问题与对策。     

转基因益生菌：预防肠道感染的新型微生态制剂

引起主要肠道疾病的许多致病菌能够特异性地利用宿主肠道细胞表面的各式寡糖,将其作为自身黏附或者分泌毒素的受体.因此,阻断致病菌及其分泌毒素与宿主靶细胞表面受体结合是一种可行的治疗方法.一类宿主肠道细胞表面受体基因重组益生菌在消化道内能够高效结合致病菌和所分泌的毒素,具有良好的预防肠道疾病的应用前景.本文主要以类志贺毒素受体重组益生茵为例,阐述转基因益生素的原理、技术及其疗效和潜在的问题与对策.     

数学模型法研究L．casei LC2W对H.pylori SS1黏附MKN-45细胞的抑制作用

目的研究干酪乳杆菌LC2W对幽门螺杆菌（H.pylori）SS1黏附MKN-45的抑制作用,探讨益生菌对致病菌拈抗的机制。方法体外培养人胃癌细胞MKN-45,采用平板计数的方法研究2株细菌的黏附性质;引入数学模型,比较LC2W与H.pylori SS1的竞争、排除和替代作用。结果运用模型可以估算出LC2W和H.pylori SS1对MKN-45最大黏附数和亲和力的大小,并可以预测在混合体系中2种菌黏附的比例;实验发现LC2W对H.pylori SS1的黏附具有很强的竞争作用和排除作用,且这2种作用存在明显的量效关系。LC2W对H.pylori SS1的黏附的替代作用不明显或过程非常缓慢。结论所采用的数学模型能较好的模拟LC2W和H.pylori SS1黏附及LC2W对H.pylori SS1黏附抑制作用,这种抑制作用主要是通过竞争性占位形成的。     

益生菌产生的细菌素及其功能机制

细菌素是细菌核糖体合成的具有抑菌活性的小肽.细菌素的产生是益生菌重要的益生特性,它们天然无毒,不仅对食品腐败菌和人体致病菌有很好的抑菌活性,还具有有助益生菌定殖和调节肠道菌群等益生特性.本文综述了益生菌产生的细菌素的种类、条件性合成、益生功能及其作用机理等,以期为深入认识益生菌的益生功能及其作用方式,研究开发对人体有益...     

益生菌防治龋病的研究进展

随着人们生活水平日益提高,口腔健康越来越受到关注。近年来,益生菌对口腔菌群和宿主健康的调节作用已成为广泛研究的话题。已有证据表明,益生菌可以竞争性地抑制口腔中致病细菌的黏附和定植,分泌抗菌物质以减少病原菌。本文综述了相关益生菌对变形链球菌这一公认的龋齿病原菌的作用,包括:(1)生物表面活性剂、细菌素、胞外多糖等益生菌代谢产物对变形链球菌牙菌生物膜的抑制作用;(2)刺激宿主免疫反应,调节口腔菌群组成;(3)下调或阻断变形链球菌细胞中与黏附在牙齿表面形成生物膜相关的基因表达。     

常见致病菌糖基转移酶的结构与功能

糖基转移酶(glycosyltransferases,GTs)将糖基从活化的供体转移到糖、脂、蛋白质和核酸等受体,其参与的蛋白质糖基化是最重要的翻译后修饰(post-translational modifications,PTMs)之一。近年来越来越多的研究证明,糖基转移酶与致病菌毒力密切相关,在致病菌的黏附、免疫逃逸和定殖等生物学过程中发挥关键作用。目前,已鉴定的糖基转移酶根据其蛋白质三维结构特征分为3种类型GT-A、GT-B和GT-C,其中常见的是GT-A和GT-B型。在致病菌中发挥黏附功能的糖基转移酶,在结构上属于GT-B或GT-C型,对致病菌表面蛋白质(黏附蛋白、自转运蛋白等)进行糖基化修饰,在致病菌黏附、生物被膜的形成和毒力机制发挥具有重要作用。糖基转移酶不仅参与致病菌黏附这一感染初始过程,其中属于GT-A型的一类致病菌糖基转移酶会进入宿主细胞,通过糖基化宿主蛋白质影响宿主信号传导、蛋白翻译和免疫应答等生物学功能。本文就常见致病菌糖基转移酶的结构及其糖基化在致病机制中的作用进行综述,着重介绍了特异性糖基化高分子量(high-molecular-weight,HMW)黏附蛋白的糖基转移酶、针对富丝氨酸重复蛋白(serine-rich repeat proteins,SRRP)糖基化修饰的糖基转移酶、细菌自转运蛋白庚糖基转移酶(bacterial autotransporter heptosyltransferase,BAHT)家族、N-糖基化蛋白质系统和进入宿主细胞发挥毒力作用的大型梭菌细胞毒素、军团菌(Legionella)葡萄糖基转移酶以及肠杆菌科的效应子NleB。为揭示致病菌中糖基转移酶致病机制的系统性研究提供参考,为未来致病菌的诊断、药物设计研发以及疫苗开发等提供科学依据和思路。     

益生菌治疗宠物细菌性腹泻概述

益生菌是一类对宿主健康有益的活体微生物,在预防、治疗和修复宠物细菌性腹泻等疾病中引起人们广泛关注。抗菌药在治疗宠物细菌性腹泻中发挥了重要作用,随着细菌耐药性加剧,严重降低了抗菌药的治疗效果。益生菌治疗细菌性腹泻具有广阔的应用前景。本文概述了宠物腹泻的致病菌种类、腹泻特征及防治现状,同时对改善宠物胃肠道疾病相关的益生菌种类、筛选条件、作用机制、存在问题及应用前景进行了介绍。     

Rhizosphere pseudomonads as probiotics improving plant health

Many root‐colonizing microbes are multifaceted in traits that improve plant health. Although isolates designated as biological control agents directly reduce pathogen growth, many exert additional beneficial features that parallel changes induced in animal and other hosts by health‐promoting microbes termed probiotics. Both animal and plant probiotics cause direct antagonism of pathogens and induce systemic immunity in the host to pathogens and other stresses. They also alter host development and improve host nutrition. The probiotic root‐colonizing pseudomonads are generalists in terms of plant hosts, soil habitats and the array of stress responses that are ameliorated in the plant. This article illustrates how the probiotic pseudomonads, nurtured by the carbon (C) and nitrogen (N) sources released by the plant in root exudates, form protective biofilms on the root surface and produce the metabolites or enzymes to boost plant health. The findings reveal the multifunctional nature of many of the microbial metabolites in the plant–probiotic interplay. The beneficial effects of probiotics on plant function can contribute to sustainable yield and quality in agricultural production.     

Evaluation of the cytoprotective effects of bovine lactoferrin against intestinal toxins using cellular model systems

This study investigated the effects of bovine lactoferrin (BLf) on the growth of different groups of bacteria in vitro. BLf showed a significant inhibitory effect on the growth of selected pathogens but not probiotics. BLf, in combination with probiotics, has the potential to influence the composition of the gut microflora via inhibition of intestinal pathogens with no significant effect on probiotic bacteria.     

In vitro evaluation of single- and multi-strain probiotics: Inter-species inhibition between probiotic strains, and inhibition of pathogens

Many studies comparing the effects of single- and multi-strain probiotics on pathogen inhibition compare treatments with different concentrations. They also do not examine the possibility of inhibition between probiotic strains with a mixture. We tested the ability of 14 single-species probiotics to inhibit each other using a cross-streak assay, and agar spot test. We then tested the ability of 15 single-species probiotics and 5 probiotic mixtures to inhibit Clostridium difficile, Escherichia coli and S. typhimurium, using the agar spot test. Testing was done with mixtures created in two ways: one group contained component species incubated together, the other group of mixtures was made using component species which had been incubated separately, equalised to equal optical density, and then mixed in equal volumes. Inhibition was observed for all combinations of probiotics, suggesting that when used as such there may be inhibition between probiotics, potentially reducing efficacy of the mixture. Significant inter-species variation was seen against each pathogen. When single species were tested against mixtures, the multi-species preparations displayed significantly (p < 0.05 or less) greater inhibition of pathogens in 12 out of 24 cases. Despite evidence that probiotic species will inhibit each other when incubated together in vitro, in many cases a probiotic mixture was more effective at inhibiting pathogens than its component species when tested at approximately equal concentrations of biomass. This suggests that using a probiotic mixture might be more effective at reducing gastrointestinal infections, and that creating a mixture using species with different effects against different pathogens may have a broader spectrum of action that a single provided by a single strain.     

Beneficial effects of probiotics in upper respiratory tract infections and their mechanical actions to antagonize pathogens

Probiotics are live micro‐organisms with beneficial effects on human health, which have the ability to counteract infections at different locations of the body. Clinical trials have shown that probiotics can be used as preventive and therapeutic agents in upper respiratory tract infections (URTIs) and otitis. Their mechanical properties allow them to aggregate and to compete with pathogens for nutrients, space and attachment to host cells. Consequently, they can directly antagonize pathogens and thus exert beneficial effects without directly affecting the metabolism of the host. An overview of the probiotics with such traits, tested up to date in clinical trials for the prevention or treatment of URTIs and otitis, is presented in this review. Their mechanical properties in the respiratory tract as well as at other locations are also cited. Species with interesting in vitro properties towards pharyngeal cells or against common respiratory pathogens have also been included. The potential safety risks of the cited species are then discussed. This review could be of help in the screening of probiotic strains with specific mechanical properties susceptible to have positive effects in clinical trials against URTIs.     

Evolving Roles of Probiotics in Cancer Prophylaxis and Therapy

In nutraceutical science, the ingestible live microbes ‘probiotics’ are regarded for their ability to confer multiplicity of health benefits on the consumers. Wide spectrum impact of these friendly microbes on the host health has been proved very frequently. They have been confirmed to boost immunity, aid in digestion, eliminate pathogens, curb inflammatory bowel diseases, moderate side effects of antibiotic therapy, lower cholesterol and blood glycemic index and produce vitamins. This review, however, focuses on the incipient, but promising area of probiotic diet-based prevention and remedy of cancer. Researchers are in universal agreement with the critical role of probiotics in getting rid of mutagens, delaying the onset of tumors, alleviating the side effects, pepping up chemotherapy, easing the postoperative complications, foiling remission and lifting the spirit of survivors. The key findings in the emerging roles of probiotics in onco-care have been summarized; the biological pathways discussed and anticipated developments in coming times are presented.     

Impact of plant derivatives on the growth of foodborne pathogens and the functionality of probiotics

Numerous studies have been published on the antimicrobial and antioxidant properties of various plant components. However, there is relatively little information on the impact of such components on the enhancement of probiotics and production of antimicrobial compounds from these probiotics. Hence, this paper focuses on the influence of plant-derived components against pathogens, enhancement of cell viability and functionality of probiotics, and potential applications of such components in food safety and human health.     

Updating the importance of lactic acid bacteria in fish farming: natural occurrence and probiotic treatments

Many recent papers have deepened the state of knowledge about lactic acid bacteria (LAB) in fish gut. In spite of high variability in fish microbiota, LAB are sometimes abundant in the intestine, notably in freshwater fish. Several strains of Streptococcus are pathogenic to fish. Streptococcus iniae and Lactococcus garvieae are major fish pathogens, against which commercial vaccines are available. Fortunately, most LAB are harmless, and some strains have been reported for beneficial effects on fish health. A major step forward in recent years was the converging evidence that LAB can stimulate the immune system in fish. An open question is whether viability can affect immunostimulation. The issue is crucial to commercialize live probiotics rather than inactivated preparations or extracts. There has been a regain of interest in allochthonous strains used as probiotics for terrestrial animals or humans, due to economical and regulatory constraints, but the short survival in sea water may limit application to marine fish. If viability is required, alternative treatments may include the incorporation of prebiotics in feed, and other dietary manipulations that could promote intestinal LAB. Antagonism to pathogens is the other main feature of candidate probiotics, and there are many reports concerning mainly carnobacteria and Enterococcus. Some bacteriocins were characterized which may be of interest not only for aquaculture, but also for food preservation.     

Review: Are we using probiotics correctly in post-weaning piglets?

Intensive farming may involve the use of diets, environments or management practices that impose physiological and psychological stressors on the animals. In particular, early weaning is nowadays a common practice to increase the productive yield of pig farms. Still, it is considered one of the most critical periods in swine production, where piglet performance can be seriously affected and where they are predisposed to the overgrowth of opportunistic pathogens. Pig producers nowadays face the challenge to overcome this situation in a context of increasing restrictions on the use of antibiotics in animal production. Great efforts are being made to find strategies to help piglets overcome the challenges of early weaning. Among them, a nutritional strategy that has received increasing attention in the last few years is the use of probiotics. It has been extensively documented that probiotics can reduce digestive disorders and improve productive parameters. Still, research in probiotics so far has also been characterized as being inconsistent and with low reproducibility from farm to farm. Scientific literature related to probiotic effects against gastrointestinal pathogens will be critically examined in this review. Moreover, the actual practical approach when using probiotics in these animals, and potential strategies to increase consistency in probiotic effects, will be discussed. Thus, considering the boost in probiotic research observed in recent years, this paper aims to provide a much-needed, in-depth review of the scientific data published to-date. Furthermore, it aims to be useful to swine nutritionists, researchers and the additive industry to critically consider their approach when developing or using probiotic strategies in weaning piglets.     

Hazard Group 3 agent decontamination using hydrogen peroxide vapour in a class III microbiological safety cabinet

Probiotics administration in aquafeed is known to increase feed consumption and absorption due to their capacity to release a wide range of digestive enzymes and nutrients which can participate in digestion process and feed utilization, along with the absorption of diet components led to an increase in host’s health and well-being. Furthermore, probiotics improve gut maturation, prevention of intestinal disorders, predigestion of antinutrient factors found in the feed ingredients, gut microbiota, disease resistance against pathogens and metabolism. The beneficial immune effects of probiotics are well established in finfish. However, in comparison, similar studies are less abundant in the shellfish. In this review, the discussions will mainly focus on studies reported the last 2 years. In recent studies, native probiotic bacteria were isolated and fed back to their hosts. Although beneficial effects were demonstrated, some studies showed adverse effects when treated with a high concentration. This adverse effect may be due to the imbalance of the gut microbiota caused by the replenished commensal probiotics. Probiotics revealed greatest effect on the shrimp digestive system particularly in the larval and early post-larval stages, and stimulate the production of endogenous enzymes in shrimp and contribute with improved the enzyme activities in the gut, as well as disease resistance.     

Can bacterial interference prevent infection?

The concept that one bacterial species can interfere with the ability of another to colonize and infect the host has at its foundation the prerequisite that bacteria must attach to biological surfaces to cause infection. Although this is an over-simplification of pathogenesis, it has led to studies aimed at creating vaccines that block adhesion events. Arguably, the use of commensal bacteria (also referred to as "normal flora", "indigenous" or "autochthonous" microorganisms) to inhibit pathogens has even greater potential than vaccine use, because these bacteria are natural competitors of pathogens and their action does not require host immune stimulation. Exogenous application of commensal organisms (probiotics) has been shown to reduce the risk of infections in the gut, urogenital tract and wound sites. To manipulate and optimize these effects, further studies are required to understand cell signaling amongst commensals and pathogens within biofilms adherent to host tissues. The potential for new therapeutic regimens using probiotics is significant and worthy of further study.