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Bifidobacteria and Their Role in the Human Gut Microbiota

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889451005 Year: Pages: 242 DOI: 10.3389/978-2-88945-100-5 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2017-07-06 13:27:36
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The human intestine is home of an almost inconceivable large number of microorganisms. The human gut microbiota can therefore be pictured as an organ placed within a host organism. The human gut microbiome, which in total may contain >100 times the number of genes present in our genome, endows us with functional features that we did not have to evolve ourselves. It is recognized that intestinal microbiota plays an important role in human health and disease. In fact, gut bacteria other than metabolize dietary components, may play complex roles such as modulation of the immune system and in reduction of gut infections. Variations in the presence and/or abundance of certain components of the intestinal microbiota have repeatedly been observed in patients that suffer from atopic diseases, inflammatory bowel disease, Crohn disease, ulcerative colitis, infectious colitis, colon cancer and diabetes. In this context, bifidobacteria represent one of the most common bacterial members of the human gut microbiota. Bifidobacteria are anaerobic, Gram-positive, irregular or branched rod-shaped bacteria that are commonly found in the gastro-intestinal tracts (GIT) of humans, especially during the first stages of life and most animal and insects. Bifidobacterial fluctuations seem directly associated with health effects and for these reasons they are being exploited as health-promoting or probiotic bacteria. However, despite the extensive commercial exploitation of bifidobacteria as probiotic bacteria, little is known about their impact or dependency on other members of the human gut microbiota or on their host. Genome analyses have highlighted the existence of gene repertoires encoding products that are responsible for the adaptation of bifidobacteria to the human intestine and intense research efforts at international level are ongoing to understand the molecular details of these interactions. Specifically, the molecular interactions that are presumed to exist between bifidobacteria and the human host, as well as interactions between different residents of intestinal microbiota are the main topic of bifidobacterial research communities.

About the Foodborne Pathogen Campylobacter

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889453887 Year: Pages: 221 DOI: 10.3389/978-2-88945-388-7 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Microbiology --- Internal medicine
Added to DOAB on : 2018-11-16 17:17:57
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A significant increase in the prevalence of campylobacteriosis cases has been observed over the past years. Campylobacter has emerged as the leading cause of bacterial foodborne disease worldwide with a significant impact on human health and an associated economic burdens. Campylobacteriosis human cases have been generally correlated with the handling, preparation and consumption of poultry. In 2017, the European Commission regulation has amended Regulation (EC) No 2073/2005 on the hygiene of foodstuffs as regards Campylobacter on broiler carcasses stating a limit of 1000 cfu/g. Campylobacter is also present in other farm animals and is frequently found on a range of foodstuffs due to cross contamination. Among the pathogenic species, C. jejuni is the most prevalent species followed by C. coli. Current guidelines highlight the importance of biosecurity but these measures are failing to mitigate the risk of pathogenic Campylobacter. As an obligate microaerophile, Campylobacter does not multiply under atmospheric oxygen concentration at ambient temperatures. It therefore constitutes a puzzle as to how it can survive from farm to retail outlets. The underlying molecular mechanisms of persistence, survival and pathogenesis appear to be unique to this pathogen. Recent research has indicated how genomic polymorphism, restricted catabolic capacity, self regulation or deregulation of genes, bacterial cooperation and unknown contamination routes may be connected to this specificity.This book includes original studies on both C. jejuni and C. coli species dealing with epidemiology and animal carriage, host interaction, control strategies, metabolism and regulation specificities of these two pathogenic species, methodology to improve cultural techniques and chicken gut microbiota challenged with Campylobacter.

Bioactive Compounds from Microbes

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889451852 Year: Pages: 142 DOI: 10.3389/978-2-88945-185-2 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2017-08-28 14:01:09
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Microorganisms have had a long and surprising history. They were “invisible” until invention of microscope in the 17th century. Until that date, although they were extensively (but inconsciously) employed in food preservation, beer and wine fermentation, cheese, vinegar, yogurt and bread making, as well as being the causative agents of infectious diseases, they were considered as “not-existing”. The work of Pasteur in the middle of the 19th century revealed several biological activities performed by microorganisms including fermentations and pathogenicity. Due to the urgent issue to treat infectious diseases (the main cause of death at those times) the “positive potential” of the microbial world has been neglected for about one century. Once the fight against the “evil” strains was fulfilled also thanks to the antibiotics, industry began to appreciate bacteria’s beneficial characteristics and exploit selected strains as starters for both food fermentations and aroma, enzyme and texturing agent production. However, it was only at the end of the 20th century that the probiotic potential of some bacteria such as lactic acid bacteria and bifidobacteria was fully recognized. Very recently, apart from the probiotic activity of in toto bacteria, attention has begun to be directed to the chemical mediators of the probiotic effect. Thanks also to the improvement of techniques such as transcriptomics, proteomics and metabolomics, several bioactive compounds are continuously being discovered. Bioactive molecules produced by bacteria, yeasts and virus-infected cells proved to be important for improving or impairing human health. The most important result of last years’ research concerns the discovery that a very complex network of signals allows communication between organisms (from intra-species interactions to inter-kingdom signaling). Based on these findings a completely new approach has arisen: the system biology standpoind. Actually, the different organisms colonizing a certain environmental niche are not merely interacting with each other as individuals but should be considered as a whole complex ecosystem continuously exchanging information at the molecular level. In this context, this topic issue explores both antagonistic compounds (i.e. antibiotics) and “multiple function” cooperative molecules improving the physiological status of both stimulators and targets of this network. From the applicative viewpoint, these molecules could be hopefully exploited to develop new pharmaceuticals and/or nutraceuticals for improving human health.

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