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1.

Lactic acid bacteria (LAB) are a heterogeneous group of Gram-positive bacteria that comprise several species which have evolved in close association with humans (food and lifestyle). While their use to ferment food dates back to very ancient times, in the last decades, LAB have attracted much attention for their documented beneficial properties and for potential biomedical applications. Some LAB are commensal that colonize, stably or transiently, host mucosal surfaces, inlcuding the gut, where they may contribute to host health. In this review, we present and discuss the main factors enabling LAB adaptation to such lifestyle, including the gene reprogramming accompanying gut colonization, the specific bacterial components involved in adhesion and interaction with host, and how the gut niche has shaped the genome of intestine-adapted species. Moreover, the capacity of LAB to colonize abiotic surfaces by forming structured communities, i.e., biofilms, is briefly discussed, taking into account the main bacterial and environmental factors involved, particularly in relation to food-related environments. The vast spread of LAB surface-associated communities and the ability to control their occurrence hold great potentials for human health and food safety biotechnologies.

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2.
The gastrointestinal tract is a complex ecosystem that associates a resident microbiota and cells of various phenotypes lining the epithelial wall expressing complex metabolic activities. The resident microbiota in the digestive tract is a heterogeneous microbial ecosystem containing up to 1 x 10(14) colony-forming units (CFUs) of bacteria. The intestinal microbiota plays an important role in normal gut function and maintaining host health. The host is protected from attack by potentially harmful microbial microorganisms by the physical and chemical barriers created by the gastrointestinal epithelium. The cells lining the gastrointestinal epithelium and the resident microbiota are two partners that properly and/or synergistically function to promote an efficient host system of defence. The gastrointestinal cells that make up the epithelium, provide a physical barrier that protects the host against the unwanted intrusion of microorganisms into the gastrointestinal microbiota, and against the penetration of harmful microorganisms which usurp the cellular molecules and signalling pathways of the host to become pathogenic. One of the basic physiological functions of the resident microbiota is that it functions as a microbial barrier against microbial pathogens. The mechanisms by which the species of the microbiota exert this barrier effect remain largely to be determined. There is increasing evidence that lactobacilli and bifidobacteria, which inhabit the gastrointestinal microbiota, develop antimicrobial activities that participate in the host's gastrointestinal system of defence. The objective of this review is to analyze the in vitro and in vivo experimental and clinical studies in which the antimicrobial activities of selected lactobacilli and bifidobacteria strains have been documented.  相似文献   

3.
Xu  Fu-Liu  Dawson  Richard W.  Tao  Shu  Cao  Jun  Li  Ben-Gang 《Hydrobiologia》2001,443(1-3):159-175
Ecosystem health is a newly proposed concept that sets new goals for environmental management. Its definition, indexing and assessment methods are still being perfected. An Ecological Modeling Method (EMM) for lake ecosystem health assessment is proposed in this paper. The EMM's procedures are: (1) to analyze the ecosystem structure of a lake in order to determine the structure and complexity of the lake's ecological model; (2) to develop a model having ecological health indicators, by designing a conceptual diagram, establishing model equations, estimating model parameters and being integrated with ecological indicators; (3) to compare the simulated and observed values of important state variables and process rates (i.e. model calibration) in order to evaluate the applicability of the model to lake ecosystem health assessment; (4) to calculate ecosystem health indicators based on the developed model; and (5) to assess lake ecosystem health according to the values of the ecosystem health indicators. The EMM was applied, as a case study, to the ecosystem health assessment of a eutrophic Chinese lake (Lake Chao) between April 1987 and March 1988. A relative order of health states from poor to good was determined as follows: August–October 1987 > April–May 1987 > June–July 1987 > November–December 1987 > January–March 1988. These results compared quite favourably with the actual current conditions at Lake Chao. The EMM method, therefore, was suitable in assessing lake ecosystem health at Lake Chao.  相似文献   

4.
The lactic acid bacteria (LAB) are safe microorganisms which are mainly used for the preparation of fermented foods and for probiotic applications. The potential of LAB as live vehicles for the production and delivery of therapeutic molecules such as antigens is also being actively investigated today. However, very little is known about the fate of live LAB when administered in vivo and about the interaction of these microorganisms with the nasal or gastrointestinal ecosystem. For future applications, it is essential to be able to discriminate the biotherapeutic strain from the endogenous microflora and to unravel the mechanisms underlying the postulated health-beneficial effect. We therefore started to investigate both aspects in a mouse model with two LAB species presently under development as live vaccine vectors, i.e., Lactococcus lactis and Lactobacillus plantarum. We have constructed different expression vectors carrying the gfp (green fluorescent protein [GFP]) gene from the jellyfish Aequoria victoria, and we found that this visible marker was best expressed when placed under the control of the inducible strong nisA promoter from L. lactis. Notably, a threshold amount of GFP was necessary to obtain a bright fluorescent phenotype. We further demonstrated that fluorescent L. plantarum NCIMB8826 can be enumerated and sorted by flow cytometry. Moreover, tagging of this strain with GFP allowed us to visualize its phagocytosis by macrophages in vitro and ex vivo and to trace it in the gastrointestinal tract of mice upon oral administration.  相似文献   

5.
Data regarding helminth communities can provide insights into health, feeding interactions, behaviour and evolution of their host organisms. Penguins (Spheniscidae) are important components of marine food webs and tracking their helminth communities can be indicative of ecosystem health. New Zealand is home to 5 of the world's 19 penguin species and little is known about their gastrointestinal helminths. Here, we provide the first study on the gastrointestinal helminths of little blue penguins from south-eastern South Island, New Zealand. The helminth community consisted of two species of tapeworm; Tetrabothrius lutzi and Tetrabothrius sp.; three nematode species, Contracaecum eudyptulae, Capillaria sp. and Stegophorus macronectes; two acanthocephalans, Andracantha sigma and Bolbosoma balaenae; and one trematode, Galactosomum otepotiense. The most prevalent parasites were T. lutzi, A. sigma, and C. eudyptulae. This work includes three new host records and five new geographic records. This is the first report of B. balaenae occurring in a host other than a marine mammal. This study adds to our knowledge about the helminth community of New Zealand little blue penguins, and includes new genetic data on helminth species, providing a baseline against which future studies may be compared.  相似文献   

6.
  1. Parasites are integral to ecosystem functioning yet often overlooked. Improved understanding of host–parasite associations is important, particularly for wide‐ranging species for which host range shifts and climate change could alter host–parasite interactions and their effects on ecosystem function.
  2. Among the most widely distributed mammals with diverse diets, gray wolves (Canis lupus) host parasites that are transmitted among canids and via prey species. Wolf–parasite associations may therefore influence the population dynamics and ecological functions of both wolves and their prey. Our goal was to identify large‐scale processes that shape host–parasite interactions across populations, with the wolf as a model organism.
  3. By compiling data from various studies, we examined the fecal prevalence of gastrointestinal parasites in six wolf populations from two continents in relation to wolf density, diet diversity, and other ecological conditions.
  4. As expected, we found that the fecal prevalence of parasites transmitted directly to wolves via contact with other canids or their excreta was positively associated with wolf density. Contrary to our expectations, the fecal prevalence of parasites transmitted via prey was negatively associated with prey diversity. We also found that parasite communities reflected landscape characteristics and specific prey items available to wolves.
  5. Several parasite taxa identified in this study, including hookworms and coccidian protozoans, can cause morbidity and mortality in canids, especially in pups, or in combination with other stressors. The density–prevalence relationship for parasites with simple life cycles may reflect a regulatory role of gastrointestinal parasites on wolf populations. Our result that fecal prevalence of parasites was lower in wolves with more diverse diets could provide insight into the mechanisms by which biodiversity may regulate disease. A diverse suite of predator–prey interactions could regulate the effects of parasitism on prey populations and mitigate the transmission of infectious agents, including zoonoses, spread via trophic interactions.
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7.
【背景】越来越多的研究发现人类的诸多疾病与肠道菌群失衡有关。乳酸菌和双歧杆菌属于肠道中的有益菌,在不同人群肠道中的多样性不尽相同。【目的】在种水平上分析健康蒙古族人群肠道菌群中乳酸菌和双歧杆菌的多样性。【方法】以27名健康蒙古族志愿者为研究对象,其中14名来自中国内蒙古,13名来自蒙古国。首次采用乳酸菌和双歧杆菌的特异性引物扩增与PacBioSMRT三代测序技术相结合,在种水平上探讨志愿者肠道中乳酸菌和双歧杆菌的丰度和生物多样性,并进一步分析性别、BMI(Bodymassindex)值和地域对上述两者可能的影响,以及优势菌种之间的相关性。【结果】在种的水平上,27名志愿者肠道样品中共鉴定到68个乳酸菌和11个双歧杆菌,其中平均相对含量在1%以上的乳酸菌有8个,包括唾液链球菌(Streptococcus salivarius,36.41%)、瘤胃乳酸杆菌(Lactobacillus ruminis,17.94%)、德氏乳杆菌(Lactobacillus delbrueckii,3.11%)、罗氏乳杆菌(Lactobacillus rogosae,2.23%)、轻型链球菌(Streptococcus mitis,2.18%)、阴道乳杆菌(Lactobacillus vaginalis,2.02%)、魏斯氏乳杆菌(Weissella confusa,1.54%)和鼠李糖乳杆菌(Lactobacillus rhamnosus,1.09%);双歧杆菌有5个,包括青春双歧杆菌(Bifidobacterium adolescentis,39.88%)、长双歧杆菌(Bifidobacterium longum,27.15%)、链状双歧杆菌(Bifidobacterium catenulatum,26.30%)、两歧双歧杆菌(B. bifidum,3.92%)和角双歧杆菌(Bifidobacterium angulatum,1.71%),聚类分析分为链状双歧杆菌和青春双歧杆菌2个主要的类群。分析结果显示:性别、BMI值和地域均未能显著影响志愿者肠道中乳酸菌和双歧杆菌的菌群结构(P0.05),但男性和女性之间、中国内蒙古地区和外蒙古国的志愿者之间的个别乳酸菌菌种相对含量存在显著差异(P0.05)。对样品中的优势乳酸菌和双歧杆菌进行Spearman相关性分析发现,乳酸菌和双歧杆菌彼此之间相关性较为密切,不同菌种间相关性不尽相同,与具体的菌种有关。【结论】首次采用PacBio SMRT测序技术在种的水平揭示了健康蒙古族人肠道中乳酸菌和双歧杆菌菌种多样性,为在种水平上解析肠道中乳酸菌和双歧杆菌多样性提供了新的研究思路和实施方案。  相似文献   

8.
AIMS: The goal of this study was to assess the genetic diversity of lactic acid bacteria (LAB) from the complex natural ecosystem present in the spontaneous fermentation of 'Almagro' eggplants by a polyphasic approach based on molecular techniques. METHODS AND RESULTS: Randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) were applied to 149 Lactobacillus isolates obtained from that fermentation process. Two random primers, OPL-05 and ArgDei-For, and two rare-cutting enzymes, SfiI and SmaI, chosen after preliminary testing on the basis of band intensity and distribution, were used. RAPD and PFGE generated electrophoretic patterns suitable for strain discrimination, but further discrimination was achieved when combined numerical analysis of the results from both methods and the results previously obtained by SDS-PAGE whole cell protein analysis, was carried out. The findings indicated a considerable degree of genomic diversity in the LAB microbiota studied and especially in the Lactobacillus plantarum isolates. In terms of species assignment, the polyphasic study allowed a definite and well-founded identification of 98.7% of the isolates. CONCLUSIONS: The combined numerical analysis of RAPD and PFGE patterns represented a useful tool to discriminate the diversity of the Lactobacillus strains responsible for the spontaneous fermentation of this pickle. The species identification and strain typing results from the polyphasic study were regarded as the most exact compromise yielding the fewest contradictions based on the available data. SIGNIFICANCE AND IMPACT OF THE STUDY: Combined numerical analysis of RAPD-PCR and PFGE patterns has not yet been employed to study the genetic diversity of LAB from an ecosystem like that found in fermenting vegetables.  相似文献   

9.
This article categorizes four kinds of adverse effects to human health caused by ecosystem change: direct, mediated, modulated, and systems failure. The effects are categorized on their scale, complexity, and lag-time. Some but not all of these can be classified as resulting from reduced ecosystem services. The articles also explores the impacts that different socioeconomic–ecologic scenarios are likely to have on human health and how changes to human health may, in turn, influence the unfolding of four different plausible future scenarios. We provide examples to show that our categorization is a useful taxonomy for understanding the complex relationships between ecosystems and human well-being and for predicting how future ecosystem changes may affect human health.Disclaimer: The views expressed in this article are those of the authors and do not necessarily reflect the position of the World Health Organization. This article has been subjected to EPA review and approved for publication but does not necessarily reflect EPA policy.  相似文献   

10.
Intraguild predation (IGP) occurs when one species preys on a competitor species that shares a common resource. Modifying a prey–predator model with prey infection, we propose a model of IG interactions among host, parasitoid, and predator, in which the predator eats parasitized and unparasitized hosts, and the adult parasitoid density is explicitly expressed. Parameter dependences of community structure, including stability of the system, were analytically obtained. Depending on interaction strength (parasitization and predation on unparasitized and parasitized hosts), the model provides six types of community structure: (1) only the host exists, (2) the host and predator coexist stably, (3) the host and parasitoid coexist stably, (4) the host–parasitoid population dynamics are unstable, (5) the three species coexist stably, and (6) the population dynamics of the three species are unstable. In contrast to a traditional prey–predator model with prey infection, which predicts that population dynamics are always locally stable, our model predicts that they are unstable when the parasitization rate is high.  相似文献   

11.
A survey of adult male Mongolian gerbils, Meriones unguiculatus (Milne-Edwards, 1867), either trapped during an expedition in Mongolia near 47 °N and 105,5 °E in June 1995 (WILD) or obtained from a laboratory strain bred in captivity since 1935 (LAB), revealed significant morphological and behavioural differences, which are likely a result of domestication in the laboratory strain. Mean body length (125.4 mm), tail length (95.5 mm) and body weight (53.6 g) was lower in WILD, although no other external characteristics were obviously different. Related allometrically to net carcass weight, organ weights were significantly lower (p < 0.01) in LAB (brain – 17.6%, eyes – 26.0%, heart – 22.3%, lungs – 43.3%). Seizures frequently seen in LAB were absent in WILD trapped (n = 167) or subsequently housed in Germany (n = 81), and rare in their offspring. Mean litter size was greater in LAB (n = 5.5) than in WILD bred in the laboratory (n = 4.4). The WILD breeding strain was named Ugoe:MU95.A genetic bottleneck (n = 9) that occurred in 1954 and remarkably smaller brains in LAB indicate that the laboratory strain has become domesticated and should be designated as “Laboratory gerbils” (M. unguiculatus forma domestica) to signify this new case of domestication among rodents.  相似文献   

12.
Cinnamoyl esterases (CEs) improve the bioavailability of caffeic acid, a potent antioxidant with beneficial health effects. This study aimed to characterize the probiotic properties of 14 strains of CE-producing lactic acid bacteria (LAB) isolated from jeot-gal, a high-salt fermented seafood. We evaluated properties of the probiotic LAB with high CE activity, including tolerance to low pH and bile salts, antimicrobial activity, surface hydrophobicity, adhesion, and immunomodulatory effects, in vitro. All LAB tested tolerated pH 2.0 and 3% Oxgall, i.e., conditions comparable with those in the gastrointestinal environment. Three isolates, Lactobacillus paracasei JBCC10650, Lactobacillus pentosus JBCC10659, and Lactobacillus plantarum JBCC10543, showed stronger adherence to epithelial cells (12.3, 9.6, and 9.4%) than a commercial probiotic Lactobacillus rhamnosus GG (9.1%; p < 0.05), and exhibited broad antibacterial activity against putative pathogens. Most of the 14 LAB strains were able to regulate mRNA expression of pro- and anti-inflammatory cytokines in macrophages, indicating their potential immunomodulatory effects. Our findings suggest that the newly isolated CE-producing probiotics may show beneficial health effects by supporting the host immune system.  相似文献   

13.
Lactic acid bacteria (LAB) are widely distributed in nature and, due to their beneficial effects on the host, are used as probiotics. This review describes the applications of LAB in animal production systems such as beekeeping, poultry, swine and bovine production, particularly as probiotics used to improve health, enhance growth and reproductive performance. Given the importance of honeybees in nature and the beekeeping industry as a producer of healthy food worldwide, the focus of this review is on the coexistence of LAB with honeybees, their food and environment. The main LAB species isolated from the beehive and their potential technological use are described. Evidence is provided that 43 LAB bacteria species have been isolated from beehives, of which 20 showed inhibition against 28 species of human and animal pathogens, some of which are resistant to antibiotics. Additionally, the presence of LAB in the beehive and their relationship with antibacterial properties of honey and pollen is discussed. Finally, we describe the use of lactic bacteria from bee colonies and their antimicrobial effect against foodborne pathogens and human health . This review broadens knowledge by highlighting the importance of honeybee colonies as suppliers of LAB and functional food.  相似文献   

14.
Effects of biodiversity on ecosystem functioning have been mainly studied in experiments that artificially create gradients in grassland plant diversity. Woody species were largely excluded from these early experiments, despite the ecological and socioeconomic importance of forest ecosystems. We discuss conceptual aspects of mechanistically driven research on the biodiversity–ecosystem functioning relationship in forests, including the comparison of scientific approaches like ‘observational studies’, ‘removal experiments’, and ‘synthetic-assemblage experiments’. We give a short overview on the differences between herbaceous and forest ecosystems, focusing on canopy characteristics, and the possibilities for individual versus population-based investigations.We present detailed information about the first large-scale, multisite and long-term biodiversity–ecosystem functioning experiment with tree species of temperate forests (BIOTREE – BIOdiversity and ecosystem processes in experimental TREE stands). At three sites of differing geology and local climate, we planted 200,000 saplings on a total area of 70 ha. At two sites, diversity gradients were established by varying the number of tree species (BIOTREE-SPECIES). At a third site, only functional diversity at a constant level of tree species richness was manipulated by selecting mixtures that differ in the functional trait values of the corresponding species (BIOTREE-FD). Additional experimental treatments at the subplot level include silvicultural management options, the addition of subdominant species, and the reduction of genetic diversity. Response variables focus on productivity, biogeochemical cycles and carbon sequestration, and resource use complementarity.We explore the use of different measures of functional diversity for a posteriori classifications of functional richness and their use in the analysis of our tree diversity experiment. The experiment is thought to provide a long-term research platform for a variety of scientific questions related to forest biodiversity and ecosystem processes.  相似文献   

15.
ABSTRACT: Lactic acid bacteria (LAB) have taken centre stage in perspectives of modern fermented food industry and probiotic based therapeutics. These bacteria encounter various stress conditions during industrial processing or in the gastrointestinal environment. Such conditions are overcome by complex molecular assemblies capable of synthesizing and/or metabolizing molecules that play a specific role in stress adaptation. Thiols are important class of molecules which contribute towards stress management in cell. Glutathione, a low molecular weight thiol antioxidant distributed widely in eukaryotes and Gram negative organisms, is present sporadically in Gram positive bacteria. However, new insights on its occurrence and role in the latter group are coming to light. Some LAB and closely related Gram positive organisms are proposed to possess glutathione synthesis and/or utilization machinery. Also, supplementation of glutathione in food grade LAB is gaining attention for its role in stress protection and as a nutrient and sulfur source. Owing to the immense benefits of glutathione, its release by probiotic bacteria could also find important applications in health improvement. This review presents our current understanding about the status of glutathione and its role as an exogenously added molecule in food grade LAB and closely related organisms.  相似文献   

16.
What is a healthy ecosystem?   总被引:21,自引:0,他引:21  
Rapid deterioration of the world's major ecosystems has intensified the need for effective environmental monitoring and the development of operational indicators of ecosystem health. Ecosystem health represents a desired endpoint of environmental management, but it requires adaptive, ongoing definition and assessment. We propose that a healthy ecosystem is one that is sustainable – that is, it has the ability to maintain its structure (organization) and function (vigor) over time in the face of external stress (resilience). Various methods to quantify these three ecosystem attributes (vigor, organization, and resilience) are discussed. These attributes are then folded into a comprehensive assessment of ecosystem health. A network analysis based ecosystem health assessment is developed and tested using trophic exchange networks representing several different aquatic ecosystems. Results indicate the potential of such an ecosystem health assessment for evaluating the relative health of similar ecosystems, and quantifying the effects of natural or anthropogenic stress on the health of a particular ecosystem over time.  相似文献   

17.
Species richness has long been used as an indicator of ecosystem functioning and health. Global richness is declining, but it is unclear whether sub‐global trends differ. Regional trends are especially understudied, with most focused on island regions where richness is strongly impacted by novel colonisations. We addressed this knowledge gap by testing for multi‐decade trends in species richness in nine open marine regions around North America (197 region‐years) while accounting for imperfect observations and grounding our findings in species‐level range dynamics. We found positive richness trends in eight of nine regions, four of which were statistically significant. Species' range sizes generally contracted pre‐extinction and expanded post‐colonisation, but the ranges of transient species expanded over the long‐term, slowly increasing their regional retention and driving increasing richness. These results provide more evidence that sub‐global richness trends are stable or increasing, and highlight the utility of range size for understanding richness dynamics.  相似文献   

18.
In this work, we aimed to characterize the antiviral response of an originally established porcine intestinal epithelial cell line (PIE cells) by evaluating the molecular innate immune response to rotavirus (RVs). In addition, we aimed to select immunomodulatory bacteria with antiviral capabilities. PIE cells were inoculated with RVs isolated from different host species and the infective titers and the molecular innate immune response were evaluated. In addition, the protection against RVs infection and the modulation of immune response by different lactic acid bacteria (LAB) strains was studied. The RVs strains OSU (porcine) and UK (bovine) effectively infected PIE cells. Our results also showed that RVs infection in PIE cells triggered TLR3-, RIG-I- and MDA-5-mediated immune responses with activation of IRF3 and NF-κB, induction of IFN-β and up-regulation of the interferon stimulated genes MxA and RNase L. Among the LAB strains tested, Bifidobacterium infantis MCC12 and B. breve MCC1274 significantly reduced RVs titers in infected PIE cells. The beneficial effects of both bifidobacteria were associated with reduction of A20 expression, and improvements of IRF-3 activation, IFN-β production, and MxA and RNase L expressions. These results indicate the value of PIE cells for studying RVs molecular innate immune response in pigs and for the selection of beneficial bacteria with antiviral capabilities.  相似文献   

19.
The commensal microbiota that inhabit different parts of the gastrointestinal (GI) tract have been shaped by coevolution with the host species. The symbiotic relationship of the hundreds of microbial species with the host requires a tuned response that prevents host damage, e.g., inflammation, while tolerating the presence of the potentially beneficial microbes. Recent studies have begun to shed light on immunological processes that participate in maintenance of homeostasis with the microbiota and on how disturbance of host immunity or the microbial ecosystem can result in disease-provoking dysbiosis. Our growing appreciation of this delicate host-microbe relationship promises to influence our understanding of inflammatory diseases and infection by microbial pathogens and to provide new therapeutic opportunities.  相似文献   

20.
The use of lactobacilli as probiotics in swine has been gaining attention due to their ability to improve growth performance and carcass quality, prevent gastrointestinal infection and most importantly, their ‘generally recognized as safe’ status. Previous studies support the potential of lactobacilli to regulate host immune systems, enhance gut metabolic capacities and maintain balance in the gut microbiota. Research on swine gut microbiota has revealed complex gut microbial community structure and showed the importance of Lactobacillus to the host's health. However, the species‐ and strain‐specific characteristics of lactobacilli that confer probiotic benefits are still not well understood. The diversity of probiotic traits in a complex gut ecosystem makes it challenging to infer the relationships between specific functions of Lactobacillus sp. and host health. In this review, we provide an overview of how lactobacilli play a pivotal role in the swine gut ecosystem and identify key characteristics that influence gut microbial community structure and the health of pigs. In addition, based on recent and ongoing meta‐omics and omics research on the gut microbiota of pigs, we suggest a workflow combining culture‐dependent and culture‐independent approaches for more effective selection of probiotic lactobacilli.  相似文献   

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