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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.

Actinobacteria in Special and Extreme Habitats: Diversity; Function Roles and Environmental Adaptations

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889450138 Year: Pages: 229 DOI: 10.3389/978-2-88945-013-8 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Microbiology
Added to DOAB on : 2018-02-27 16:16:44
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Actinobacteria are highly diverse prokaryotes that are ubiquitous in soil, freshwater and marine ecosystems. Although various studies have focused on the ecology of this phylum, data are still scant on the diversity, abundance and ecology of actinobacteria endemic to special and extreme environments, such as gut, plant, alkaline saline soil, deep sea sediments, hot springs and other habitats. Actinobacteria are well-known producers of a vast array of secondary metabolites, many of which have useful applications in medicine and agriculture. Furthermore, actinobacteria also have diverse functions in different environments apart from antibiotic production. For example, actinobacteria are reported to contribute to the break-down and recycling of organic compounds. They play a significant role in fixation of nitrogen, improvement plant growth, biodegradation, bioremediation and environmental protection. Therefore, understanding the actinobacterial diversity and distribution in such special environments is important in deciphering the ecological roles of these microorganisms and for biotechnological bioprospecting. Recent advances in cultivation, DNA sequencing technologies and -omics (metagenomics, metaproteomics etc) methods have greatly contributed to the rapid advancement of our understanding of microbial diversity, function and they interactions with environment. Furthermore, comparative genomic studies can provide overall information about actinobacterial speciation, evolution, metabolism and environment adaptation mechanisms. This research topic comprising reviews and original articles highlights the recent advances regarding the unexpectedly diverse/rare group of actinobacteria with special selective isolation methods or culture-independent methods, as well as their biological activities, ecophysiologica function and mechanisms from diverse special and extreme environments.

Advances in Aspergillus fumigatus pathobiology

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889197897 Year: Pages: 109 DOI: 10.3389/978-2-88919-789-7 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2016-04-07 11:22:02
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Aspergillus fumigatus is a human fungal pathogen that causes invasive aspergillosis (IA), a major infectious cause of death in the expanding population of immunocompromised individuals such as cancer patients and transplant recipients. The mortality of IA remains high (30-70%) and emerging resistance to triazoles, the first-line antifungal drug class, is of particular concern. Second-line therapies for IA are limited by their toxicity (polyenes) or their lack of fungicidal activity (echinocandins). Identification of novel antifungal targets is an urgent need for improving the outcome of IA. A. fumigatus is a filamentous fungus exhibiting a complex developmental cycle and elaborated mechanisms of adaptation to allow the initiation and progression of infection in the human host. The fungal cell wall, with its unique and dynamic structure, is crucial for protecting cell integrity and evading the host immune system, also contributing to biofilm formation and virulence, and thus representing an ideal antifungal target. The emergence of azole resistance implies various and complex mechanisms that need to be further elucidated. Other important processes, such as biosynthetic pathways and toxin/metabolite production are important for fungal survival and propagation in the host environment, ultimately leading to disease. Moreover, the host immune response is a determinant factor in influencing the course of infection. The objective of this topic issue is to provide an overview of the recent advances in our understanding of A. fumigatus pathobiology and of IA pathogenesis to outline future research.

Agrobacterium biology and its application to transgenic plant production

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889195749 Year: Pages: 165 DOI: 10.3389/978-2-88919-574-9 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General) --- Botany
Added to DOAB on : 2016-02-05 17:24:33
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The broad host range pathogenic bacterium Agrobacterium tumefaciens has been widely studied as a model system to understand horizontal gene flow, secretion of effector proteins into host cells, and plant-pathogen interactions. Agrobacterium-mediated plant transformation also is the major method for generating transgenic plants for research and biotechnology purposes. Agrobacterium species have the natural ability to conduct interkingdom genetic transfer from bacteria to eukaryotes, including most plant species, yeast, fungi, and even animal cells. In nature, A. tumefaciens causes crown gall disease resulting from expression in plants of auxin and cytokinin biosynthesis genes encoded by the transferred (T-) DNA. Gene transfer from A. tumefaciens to host cells requires virulence (vir) genes that reside on the resident tumor-inducing (Ti) plasmid. In addition to T-DNA, several Virulence (Vir) effector proteins are also translocated to host cells through a bacterial type IV secretion system. These proteins aid in T-DNA trafficking through the host cell cytoplasm, nuclear targeting, and T-DNA integration. Genes within native T-DNAs can be replaced by any gene of interest, making Agrobacterium species important tools for plant research and genetic engineering. In this research topic, we provided updated information on several important areas of Agrobacterium biology and its use for biotechnology purposes.

Anaerobic Digestion

Authors: --- --- --- --- et al.
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889456796 Year: Pages: 152 DOI: 10.3389/978-2-88945-679-6 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Microbiology --- General and Civil Engineering --- Biotechnology --- Environmental Sciences
Added to DOAB on : 2019-01-23 14:53:43
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Anaerobic digestion (AD) is a naturally-occurring biological process in soils, sediments, ruminants, and several other anoxic environments, that cycles carbon and other nutrients, and converts organic matter into a methane-rich gas. As a biotechnology, AD is now well-established for the treatment of the organic fraction of various waste materials, including wastewaters, but is also increasingly applied for an expanding range of organic feedstocks suitable for biological conversion to biogas. AD applications are classified in various ways, including on the basis of bioreactor design; and operating parameters, such as retention time, temperature, pH, total solids (TS) and volatile solids (VS) contents, and biodegradability of substrates. AD is an attractive bioenergy and waste / wastewater treatment technology. The advantages of AD for waste treatment include: production of a useable fuel (biogas/methane); possibility of high organic loading; reduced carbon footprint; and suitability for integration into a wide variety of process configurations and scales. Specifically, two important, and developing, applications exemplify the potential of AD technologies: (1) the integration of AD as the basis of the core technologies underpinning municipal wastewater, and sewage, treatment, to displace less sustainable, and more energy-intensive, aerobic biological treatment systems in urban water infrastructures; and (2) technical innovations for higher-rate conversions of high-solids wastestreams, and feedstocks, for the production of energy carriers (i.e. methane-biogas, but possibly also biohydrogen) and other industrially-relevant intermediates, such as organic acids. Internationally, the research effort to maximize AD biogas yield has increased ten-fold over the past decade. Depending on the feedstocks, bioreactor design and process parameters, fundamental and applied knowledge are still required to improve conversion rates and biogas yields. This Research Topic cover aspects related to AD processes, such as the effect of feedstock composition, as well as the effect of feedstock pre-treatment, bioreactor design and operating modes, on process efficiency; microbial community dynamics and systems biology; influence of macro- and micro-nutrient concentrations and availability; process control; upgrading and calibration of anaerobic digestion models (e.g. ADM1) considering the biochemical routes as well as the hydrodynamics in such ecosystems; and novel approaches to process monitoring, such as the development, and application, of novel, and rapid diagnostic assays, including those based on molecular microbiology. Detailed full-scale application studies were also particularly welcomed.

Animal model studies on viral infections

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889194568 Year: Pages: 173 DOI: 10.3389/978-2-88919-456-8 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2016-02-05 17:24:33
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Understanding viral replication and pathogenicity properties in infected individuals is a major mission of animal virology. Animal models are essential to analyze the in vivo viral characteristics and to develop countermeasures against viruses. To fight against a wide variety of viruses, basic studies with specific and/ or common approaches are required. This Research Topic collects articles that describe studies on numerous virus species at various stages toward animal experiments: (i) description/evaluation/ new challenges of animal model studies; (ii) experimental material/methods for animal model studies; (iii) observations for upcoming animal model studies. Numbers of DNA and RNA viruses such as HHV-6, HPV, Ebola virus, HCV, dengue virus, HTLV-1, HIV-1, SIV, and measles virus are covered by this special issue consisting of original research, methods, review, mini-review, and opinion articles. All readers would understand, we believe and hope, that animal model studies are critical for current virology as always.

Anthropogenic Impacts on the Microbial Ecology and Function of Aquatic Environments

Authors: --- --- ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889199396 Year: Pages: 248 DOI: 10.3389/978-2-88919-939-6 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Microbiology
Added to DOAB on : 2016-01-19 14:05:46
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Aquatic ecosystems are currently experiencing unprecedented levels of impact from human activities including over-exploitation of resources, habitat destruction, pollution and the influence of climate change. The impacts of these activities on the microbial ecology of aquatic environments are only now beginning to be defined. One of the many implications of environmental degradation and climate change is the geographical expansion of disease- causing microbes such as those from the Vibrio genus. Elevating sea surface temperatures correlate with increasing Vibrio numbers and disease in marine animals (e.g. corals) and humans. Contamination of aquatic environments with heavy metals and other pollutants affects microbial ecology with downstream effects on biogeochemical cycles and nutrient turnover. Also of importance is the pollution of aquatic environments with antibiotics, resistance genes and the mobile genetic elements that house resistance genes from human and animal waste. Such contaminated environments act as a source of resistance genes long after an antibiotic has ceased being used in the community. Environments contaminated with mobile genetic elements that are adapted to human commensals and pathogens function to capture new resistance genes for potential reintroduction back into clinical environments. This research topic encompasses these diverse topics and describes the affect(s) of human activity on the microbial ecology and function in aquatic environments and, describes methods of restoration and for modelling disturbances.

Antibiotic Resistance in Aquatic Systems

Authors: --- --- ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889451319 Year: Pages: 107 DOI: 10.3389/978-2-88945-131-9 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2017-07-06 13:27:36
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Rivers, lakes and the ocean receive antibiotic resistance genes from human environments. The aquatic environments are a huge reservoir and exchange stage of antibiotic resistance genes.

Antifungal Drug Discovery: New Theories and New Therapies

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889199501 Year: Pages: 136 DOI: 10.3389/978-2-88919-950-1 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2016-01-19 14:05:46
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Fungal infections such as candidoses can range from superficial mucous membrane infection to life-threatening systemic mycoses. Candida infections are a significant clinical problem globally due to rapid rise in compromised host populations including HIV/AIDS, organ transplant recipients and patients on chemotherapy. In addition, sharp increase in aging populations which are susceptible to fungal infections is expected in next few decades. Antifungal drugs are relatively difficult to develop compared to the antibacterial drugs owing to the eukaryotic nature of the cells. Therefore, only a handful of antifungal agents are currently available to treat the myriad of fungal infections. Moreover, rising antifungal resistance and host-related adverse reactions have limited the antifungal arsenal against fungal pathogens. In this research topic, we tried to update the theoretical aspects pertaining to the antifungal drug discovery i.e. proposed novel mechanisms, new drug targets and pathways. In addition, invited authors explored the new antifungal drugs derived from natural and synthetic sources which are currently under development. Contributors were encouraged to bring new insight into the antifungal drug discovery. We hope the reader may arrive at a general consensus on the possible strategies to combat ever increasing ubiquitous fungal infection in this new century.

Antimicrobial compounds from natural sources

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889192595 Year: Pages: 149 DOI: 10.3389/978-2-88919-259-5 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Microbiology
Added to DOAB on : 2015-12-03 13:02:24
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The nature is a generous source of a number of compounds with potential application for the treatment of several diseases including the infectious diseases, which is of utmost concern for the modern medicine due to the observed striding antimicrobial resistance. A number of sources of natural compounds with valuable and clinical antimicrobial activity can be listed, comprising medicinal plants, marine and terrestrial organisms, which includes fungi and bacteria. Nevertheless, there is still a vast fauna and flora that, once systematically explored, could provide additional antimicrobial leads and drugs. Investigators were invited to contribute with original research and/or review articles on this area, specifically with studies exploiting the mechanism of action and the structure-activity aspects of natural compounds with antimicrobial activity that provides insights on potential ways to overcome the antimicrobial resistance. Therefore, thanks to the contribution of active researchers in the field, several scientific studies mainly focused on natural products with antimicrobial activity are presented in this Research Topic Ebook.

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