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  • 1
    Online Resource
    Online Resource
    Contrasting Patterns of Functional Diversity in Coffee Root Fungal Communities Associated with Organic and Conventionally Managed Fields
    American Society for Microbiology ; 2020
    In:  Applied and Environmental Microbiology Vol. 86, No. 11 ( 2020-05-19)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 86, No. 11 ( 2020-05-19)
    Abstract: The structure and function of fungal communities in the coffee rhizosphere are influenced by crop environment. Because coffee can be grown along a management continuum from conventional application of pesticides and fertilizers in full sun to organic management in a shaded understory, we used coffee fields to hold host constant while comparing rhizosphere fungal communities under markedly different environmental conditions with regard to shade and inputs. We characterized the shade and soil environment in 25 fields under conventional, organic, or transitional management in two regions of Costa Rica. We amplified the internal transcribed spacer 2 (ITS2) region of fungal DNA from coffee roots in these fields and characterized the rhizosphere fungal community via high-throughput sequencing. Sequences were assigned to guilds to determine differences in functional diversity and trophic structure among coffee field environments. Organic fields had more shade, a greater richness of shade tree species, and more leaf litter and were less acidic, with lower soil nitrate availability and higher soil copper, calcium, and magnesium availability than conventionally managed fields, although differences between organic and conventionally managed fields in shade and calcium and magnesium availability depended on region. Differences in richness and community composition of rhizosphere fungi between organic and conventionally managed fields were also correlated with shade, soil acidity, and nitrate and copper availability. Trophic structure differed with coffee field management. Saprotrophs, plant pathogens, and mycoparasites were more diverse, and plant pathogens were more abundant, in organic than in conventionally managed fields, while saprotroph-plant pathogens were more abundant in conventionally managed fields. These differences reflected environmental differences and depended on region. IMPORTANCE Rhizosphere fungi play key roles in ecosystems as nutrient cyclers, pathogens, and mutualists, yet little is currently known about which environmental factors and how agricultural management may influence rhizosphere fungal communities and their functional diversity. This field study of the coffee agroecosystem suggests that organic management not only fosters a greater overall diversity of fungi, but it also maintains a greater richness of saprotrophic, plant-pathogenic, and mycoparasitic fungi that has implications for the efficiency of nutrient cycling and regulation of plant pathogen populations in agricultural systems. As well as influencing community composition and richness of rhizosphere fungi, shade management and use of fungicides and synthetic fertilizers altered the trophic structure of the coffee agroecosystem.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.00052-20
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2020
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    The Geographic Structure of Viruses in the Cuatro Ciénegas Basin, a Unique Oasis in Northern Mexico, Reveals a Highly Diverse Population on a Small Geographic Scale
    American Society for Microbiology ; 2018
    In:  Applied and Environmental Microbiology Vol. 84, No. 11 ( 2018-06)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 84, No. 11 ( 2018-06)
    Abstract: The Cuatro Ciénegas Basin (CCB) is located in the Chihuahuan desert in the Mexican state of Coahuila; it has been characterized as a site with high biological diversity despite its extreme oligotrophic conditions. It has the greatest number of endemic species in North America, containing abundant living microbialites (including stromatolites and microbial mats) and diverse microbial communities. With the hypothesis that this high biodiversity and the geographic structure should be reflected in the virome, the viral communities in 11 different locations of three drainage systems, Churince, La Becerra, and Pozas Rojas, and in the intestinal contents of 3 different fish species, were analyzed for both eukaryotic and prokaryotic RNA and DNA viruses using next-generation sequencing methods. Double-stranded DNA (dsDNA) virus families were the most abundant (72.5% of reads), followed by single-stranded DNA (ssDNA) viruses (2.9%) and ssRNA and dsRNA virus families (0.5%). Thirteen families had dsDNA genomes, five had ssDNA, three had dsRNA, and 16 had ssRNA. A highly diverse viral community was found, with an ample range of hosts and a strong geographical structure, with very even distributions and signals of endemicity in the phylogenetic trees from several different virus families. The majority of viruses found were bacteriophages but eukaryotic viruses were also frequent, and the large diversity of viruses related to algae were a surprise, since algae are not evident in the previously analyzed aquatic systems of this ecosystem. Animal viruses were also frequently found, showing the large diversity of aquatic animals in this oasis, where plants, protozoa, and archaea are rare. IMPORTANCE In this study, we tested whether the high biodiversity and geographic structure of CCB is reflected in its virome. CCB is an extraordinarily biodiverse oasis in the Chihuahuan desert, where a previous virome study suggested that viruses had followed the marine ancestry of the marine bacteria and, as a result of their long isolation, became endemic to the site. In this study, which includes a larger sequencing coverage and water samples from other sites within the valley, we confirmed the high virus biodiversity and uniqueness as well as the strong biogeographical diversification of the CCB. In addition, we also analyzed fish intestinal contents, finding that each fish species eats different prey and, as a result, presents different viral compositions even if they coexist in the same pond. These facts highlight the high and novel virus diversity of CCB and its “lost world” status.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.00465-18
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Functional Analysis of the Glucan Degradation Locus in Caldicellulosiruptor bescii Reveals Essential Roles of Component Glycoside Hydrolases in Plant Biomass Deconstruction
    American Society for Microbiology ; 2017
    In:  Applied and Environmental Microbiology Vol. 83, No. 24 ( 2017-12-15)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 83, No. 24 ( 2017-12-15)
    Abstract: The ability to hydrolyze microcrystalline cellulose is an uncommon feature in the microbial world, but it can be exploited for conversion of lignocellulosic feedstocks into biobased fuels and chemicals. Understanding the physiological and biochemical mechanisms by which microorganisms deconstruct cellulosic material is key to achieving this objective. The glucan degradation locus (GDL) in the genomes of extremely thermophilic Caldicellulosiruptor species encodes polysaccharide lyases (PLs), unique cellulose binding proteins (tāpirins), and putative posttranslational modifying enzymes, in addition to multidomain, multifunctional glycoside hydrolases (GHs), thereby representing an alternative paradigm for plant biomass degradation compared to fungal or cellulosomal systems. To examine the individual and collective in vivo roles of the glycolytic enzymes, the six GH genes in the GDL of Caldicellulosiruptor bescii were systematically deleted, and the extents to which the resulting mutant strains could solubilize microcrystalline cellulose (Avicel) and plant biomass (switchgrass or poplar) were examined. Three of the GDL enzymes, Athe_1867 (CelA) (GH9-CBM3-CBM3-CBM3-GH48), Athe_1859 (GH5-CBM3-CBM3-GH44), and Athe_1857 (GH10-CBM3-CBM3-GH48), acted synergistically in vivo and accounted for 92% of naked microcrystalline cellulose (Avicel) degradation. However, the relative importance of the GDL GHs varied for the plant biomass substrates tested. Furthermore, mixed cultures of mutant strains showed that switchgrass solubilization depended on the secretome-bound enzymes collectively produced by the culture, not on the specific strain from which they came. These results demonstrate that certain GDL GHs are primarily responsible for the degradation of microcrystalline cellulose-containing substrates by C. bescii and provide new insights into the workings of a novel microbial mechanism for lignocellulose utilization. IMPORTANCE The efficient and extensive degradation of complex polysaccharides in lignocellulosic biomass, particularly microcrystalline cellulose, remains a major barrier to its use as a renewable feedstock for the production of fuels and chemicals. Extremely thermophilic bacteria from the genus Caldicellulosiruptor rapidly degrade plant biomass to fermentable sugars at temperatures of 70 to 78°C, although the specific mechanism by which this occurs is not clear. Previous comparative genomic studies identified a genomic locus found only in certain Caldicellulosiruptor species that was hypothesized to be mainly responsible for microcrystalline cellulose degradation. By systematically deleting genes in this locus in Caldicellulosiruptor bescii , the nuanced, substrate-specific in vivo roles of glycolytic enzymes in deconstructing crystalline cellulose and plant biomasses could be discerned. The results here point to synergism of three multidomain cellulases in C. bescii , working in conjunction with the aggregate secreted enzyme inventory, as the key to the plant biomass degradation ability of this extreme thermophile.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.01828-17
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2017
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    Dynamic Gut Microbiome Changes in Response to Low-Iron Challenge
    American Society for Microbiology ; 2021
    In:  Applied and Environmental Microbiology Vol. 87, No. 3 ( 2021-01-15)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 87, No. 3 ( 2021-01-15)
    Abstract: Iron is an essential micronutrient for life. In mammals, dietary iron is absorbed primarily in the small intestine. Currently, the impacts of dietary iron on the taxonomic structure and function of the gut microbiome and reciprocal effects on the animal host are not well understood. Here, we establish a mouse model of low-iron challenge in which intestinal biomarkers and reduced fecal iron reveal iron stress while serum iron and mouse behavioral markers indicate maintenance of iron homeostasis. We show that the diversity of the gut microbiome in conventional C57BL/6 mice changes dramatically during 2 weeks on a low-iron diet. We also show the effects of a low-iron diet on microbiome diversity are long lasting and not easily recovered when iron is returned to the diet. Finally, after optimizing taxon association methods, we show that some bacteria are unable to fully recover after the low-iron challenge and appear to be extirpated from the gut entirely. In particular, operational taxonomic units (OTUs) from the Prevotellaceae and Porphyromonadaceae families and Bacteroidales order are highly sensitive to low-iron conditions, while other seemingly insensitive OTUs recover. These results provide new insights into the iron requirements of gut microbiome members and add to the growing understanding of mammalian iron cycling. IMPORTANCE All cells need iron. Both too much and too little iron lead to diseases and unwanted outcomes. Although the impact of dietary iron on human cells and tissues has been well studied, there is currently a lack of understanding about how different levels of iron influence the abundant and diverse members of the human microbiome. This study develops a well-characterized mouse model for studying low-iron levels and identifies key groups of bacteria that are most affected. We found that the microbiome undergoes large changes when iron is removed from the diet but that many individual bacteria are able to rebound when iron levels are changed back to normal. That said, a select few members, referred to as iron-sensitive bacteria, seem to be lost. This study begins to identify individual members of the mammalian microbiome most affected by changes in dietary iron levels.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.02307-20
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Growth of thermophilic acetogenic bacteria on methoxylated aromatic acids
    Oxford University Press (OUP) ; 1988
    In:  FEMS Microbiology Letters Vol. 52, No. 1-2 ( 1988-07), p. 25-28
    Details
    In: FEMS Microbiology Letters, Oxford University Press (OUP), Vol. 52, No. 1-2 ( 1988-07), p. 25-28
    Type of Medium: Online Resource
    ISSN: 0378-1097 , 1574-6968
    URL: Issue
    URL: Article
    DOI: 10.1111/fml.1988.52.issue-1-2
    DOI: 10.1111/j.1574-6968.1988.tb02566.x
    RVK:
    WA 15000
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 1988
    detail.hit.zdb_id: 1501716-3
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    Shewanella oneidensis MR-1 Utilizes both Sodium- and Proton-Pumping NADH Dehydrogenases during Aerobic Growth
    American Society for Microbiology ; 2018
    In:  Applied and Environmental Microbiology Vol. 84, No. 12 ( 2018-06-15)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 84, No. 12 ( 2018-06-15)
    Abstract: Shewanella oneidensis MR-1 is a metal-reducing bacterium with the ability to utilize many different terminal electron acceptors, including oxygen and solid-metal oxides. Both metal oxide reduction and aerobic respiration have been studied extensively in this organism. However, electron transport chain processes upstream of the terminal oxidoreductases have been relatively understudied in this organism, especially electron transfer from NADH to respiratory quinones. Genome annotation indicates that S. oneidensis MR-1 encodes four NADH dehydrogenases, a proton-translocating dehydrogenase (Nuo), two sodium ion-translocating dehydrogenases (Nqr1 and Nqr2), and an “uncoupling” dehydrogenase (Ndh), but none of these complexes have been studied. Therefore, we conducted a study specifically focused on the effects of individual NADH dehydrogenase knockouts in S. oneidensis MR-1. We observed that two of the single-mutant strains, the Δ nuoN and Δ nqrF1 mutants, exhibited significant growth defects compared with the wild type. However, the defects were minor and only apparent under certain growth conditions. Further testing of the Δ nuoN Δ nqrF1 double-mutant strain yielded no growth in minimal medium under oxic conditions, indicating that Nuo and Nqr1 have overlapping functions, but at least one is necessary for aerobic growth. Coutilization of proton- and sodium ion-dependent energetics has important implications for the growth of this organism in environments with varied pH and salinity, including microbial electrochemical systems. IMPORTANCE Bacteria utilize a wide variety of metabolic pathways that allow them to take advantage of different energy sources, and to do so with varied efficiency. The efficiency of a metabolic process determines the growth yield of an organism, or the amount of biomass it produces per amount of substrate consumed. This parameter has important implications in biotechnology and wastewater treatment, where low growth yields are often preferred to minimize the production of microbial biomass. In this study, we investigated respiratory pathways containing NADH dehydrogenases with varied efficiency (i.e., the number of ions translocated per NADH oxidized) in the metal-reducing bacterium Shewanella oneidensis MR-1. We observed that two different respiratory pathways are used concurrently, and at least one pathway must be functional for growth under oxic conditions.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.00415-18
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 7
    Online Resource
    Online Resource
    Development of Multiwell-Plate Methods Using Pure Cultures of Methanogens To Identify New Inhibitors for Suppressing Ruminant Methane Emissions
    American Society for Microbiology ; 2017
    In:  Applied and Environmental Microbiology Vol. 83, No. 15 ( 2017-08)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 83, No. 15 ( 2017-08)
    Abstract: Hydrogenotrophic methanogens typically require strictly anaerobic culturing conditions in glass tubes with overpressures of H 2 and CO 2 that are both time-consuming and costly. To increase the throughput for screening chemical compound libraries, 96-well microtiter plate methods for the growth of a marine (environmental) methanogen Methanococcus maripaludis strain S2 and the rumen methanogen Methanobrevibacter species AbM4 were developed. A number of key parameters (inoculum size, reducing agents for medium preparation, assay duration, inhibitor solvents, and culture volume) were optimized to achieve robust and reproducible growth in a high-throughput microtiter plate format. The method was validated using published methanogen inhibitors and statistically assessed for sensitivity and reproducibility. The Sigma-Aldrich LOPAC library containing 1,280 pharmacologically active compounds and an in-house natural product library (120 compounds) were screened against M. maripaludis as a proof of utility. This screen identified a number of bioactive compounds, and MIC values were confirmed for some of them against M. maripaludis and M. AbM4. The developed method provides a significant increase in throughput for screening compound libraries and can now be used to screen larger compound libraries to discover novel methanogen-specific inhibitors for the mitigation of ruminant methane emissions. IMPORTANCE Methane emissions from ruminants are a significant contributor to global greenhouse gas emissions, and new technologies are required to control emissions in the agriculture technology (agritech) sector. The discovery of small-molecule inhibitors of methanogens using high-throughput phenotypic (growth) screening against compound libraries (synthetic and natural products) is an attractive avenue. However, phenotypic inhibitor screening is currently hindered by our inability to grow methanogens in a high-throughput format. We have developed, optimized, and validated a high-throughput 96-well microtiter plate assay for growing environmental and rumen methanogens. Using this platform, we identified several new inhibitors of methanogen growth, demonstrating the utility of this approach to fast track the development of methanogen-specific inhibitors for controlling ruminant methane emissions.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.00396-17
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2017
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 8
    Online Resource
    Online Resource
    A Simple In Vitro Gut Model for Studying the Interaction between Escherichia coli and the Intestinal Commensal Microbiota in Cecal Mucus
    American Society for Microbiology ; 2018
    In:  Applied and Environmental Microbiology Vol. 84, No. 24 ( 2018-12-15)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 84, No. 24 ( 2018-12-15)
    Abstract: A novel in vitro gut model was developed to better understand the interactions between Escherichia coli and the mouse cecal mucus commensal microbiota. The gut model is simple and inexpensive while providing an environment that largely replicates the nonadherent mucus layer of the mouse cecum. 16S rRNA gene profiling of the cecal microbial communities of streptomycin-treated mice colonized with E. coli MG1655 or E. coli Nissle 1917 and the gut model confirmed that the gut model properly reflected the community structure of the mouse intestine. Furthermore, the results from the in vitro gut model mimic the results of published in vivo competitive colonization experiments. The gut model is initiated by the colonization of streptomycin-treated mice, and then the community is serially transferred in microcentrifuge tubes in an anaerobic environment generated in anaerobe jars. The nutritional makeup of the cecum is simulated in the gut model by using a medium consisting of porcine mucin, mouse cecal mucus, HEPES-Hanks buffer (pH 7.2), Cleland’s reagent, and agarose. Agarose was found to be essential for maintaining the stability of the microbial community in the gut model. The outcome of competitions between E. coli strains in the in vitro gut model is readily explained by the “restaurant hypothesis” of intestinal colonization. This simple model system potentially can be used to more fully understand how different members of the microbiota interact physically and metabolically during the colonization of the intestinal mucus layer. IMPORTANCE Both commensal and pathogenic strains of Escherichia coli appear to colonize the mammalian intestine by interacting physically and metabolically with other members of the microbiota in the mucus layer that overlays the cecal and colonic epithelium. However, the use of animal models and the complexity of the mammalian gut make it difficult to isolate experimental variables that might dictate the interactions between E. coli and other members of the microbiota, such as those that are critical for successful colonization. Here, we describe a simple and relatively inexpensive in vitro gut model that largely mimics in vivo conditions and therefore can facilitate the manipulation of experimental variables for studying the interactions of E. coli with the intestinal microbiota.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.02166-18
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 9
    Online Resource
    Online Resource
    Sea Cucumber Intestinal Regeneration Reveals Deterministic Assembly of the Gut Microbiome
    American Society for Microbiology ; 2020
    In:  Applied and Environmental Microbiology Vol. 86, No. 14 ( 2020-07-02)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 86, No. 14 ( 2020-07-02)
    Abstract: The gut microbiome has far-reaching effects on host organism health, so understanding the processes that underlie microbial community assembly in the developing gut is a current research priority. Here, a holothurian (also known as sea cucumber; phylum Echinodermata) host is explored as a promising model system for studying the assembly of the gut microbiome. Holothurians have a unique capacity for evisceration (expulsion of the internal organs), followed by rapid regeneration of the gut, decoupling host ontogeny from gut tissue development and permitting experimental manipulation of the gut microbiome in mature host individuals. Here, evisceration was induced in the sea cucumber Sclerodactyla briareus , and regenerating stomach and intestine microbiomes were characterized before and on days 0, 13, 17, and 20 after evisceration using Illumina sequencing of 16S rRNA genes. Regenerating stomach and intestine tissues had microbial communities significantly different from those of mature tissues, with much higher alpha diversity and evenness of taxa in regenerating tissues. Despite immersion in a diverse pool of sediment and seawater microbes in flowthrough seawater aquaria, regenerating gut microbiomes differed at each stage of regeneration and displayed a highly similar community structure among replicates, providing evidence for deterministic host selection of a specific microbial consortium. Moreover, regenerating gut tissues acquired a microbiome that likely conferred energetic and immune advantages to the sea cucumber host, including microbes that can fix carbon and degrade invading pathogens. IMPORTANCE The gut microbiome is pertinent to many aspects of animal health, and there is a great need for natural but tractable experimental systems to examine the processes shaping gut microbiome assembly. Here, the holothurian (sea cucumber) Sclerodactyla briareus was explored as an experimental system to study microbial colonization in the gut, as S. briareus individuals have the ability to completely eviscerate and rapidly regenerate their digestive organs. After induced evisceration, microbial community assembly was characterized over 20 days in regenerating animals. This study demonstrated that colonization of the sea cucumber gut was deterministic; despite immersion in a diverse consortium of environmental microbes, a specific subset of microbes proliferated in the gut, including taxa that likely conferred energetic and immune advantages to the host. Sea cucumbers have the potential to revolutionize our understanding of gut microbiome assembly, as rapid and repeatable gut tissue regeneration provides a promising and tractable experimental system.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.00489-20
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2020
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 10
    Online Resource
    Online Resource
    The Type IX Secretion System Is Required for Virulence of the Fish Pathogen Flavobacterium columnare
    American Society for Microbiology ; 2017
    In:  Applied and Environmental Microbiology Vol. 83, No. 23 ( 2017-12)
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 83, No. 23 ( 2017-12)
    Abstract: Flavobacterium columnare , a member of the phylum Bacteroidetes , causes columnaris disease in wild and aquaculture-reared freshwater fish. The mechanisms responsible for columnaris disease are not known. Many members of the phylum Bacteroidetes use type IX secretion systems (T9SSs) to secrete enzymes, adhesins, and proteins involved in gliding motility. The F. columnare genome has all of the genes needed to encode a T9SS. gldN , which encodes a core component of the T9SS, was deleted in wild-type strains of F. columnare . The F. columnare Δ gldN mutants were deficient in the secretion of several extracellular proteins and lacked gliding motility. The Δ gldN mutants exhibited reduced virulence in zebrafish, channel catfish, and rainbow trout, and complementation restored virulence. PorV is required for the secretion of a subset of proteins targeted to the T9SS. An F. columnare Δ porV mutant retained gliding motility but exhibited reduced virulence. Cell-free spent media from exponentially growing cultures of wild-type and complemented strains caused rapid mortality, but spent media from Δ gldN and Δ porV mutants did not, suggesting that soluble toxins are secreted by the T9SS. IMPORTANCE Columnaris disease, caused by F. columnare , is a major problem for freshwater aquaculture. Little is known regarding the virulence factors produced by F. columnare , and control measures are limited. Analysis of targeted gene deletion mutants revealed the importance of the type IX protein secretion system (T9SS) and of secreted toxins in F. columnare virulence. T9SSs are common in members of the phylum Bacteroidetes and likely contribute to the virulence of other animal and human pathogens.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.01769-17
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2017
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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