Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Language
Year
  • 1
    Language: English
    In: Applied and environmental microbiology, December 2013, Vol.79(23), pp.7220-8
    Description: Members of the Lactobacillus acidophilus complex are associated with functional foods and dietary supplements because of purported health benefits they impart to the consumer. Many characteristics of these microorganisms are reported to be strain specific. Therefore, proper strain typing is essential for safety assessment and product labeling, and also for monitoring strain integrity for industrial production purposes. Fifty-two strains of the L. acidophilus complex (L. acidophilus, L. amylovorus, L. crispatus, L. gallinarum, L. gasseri, and L. johnsonii) were genotyped using two established methods and compared to a novel multilocus sequence typing (MLST) scheme. PCR restriction fragment length polymorphism (PCR-RFLP) analysis of the hsp60 gene with AluI and TaqI successfully clustered 51 of the 52 strains into the six species examined, but it lacked strain-level discrimination. Random amplified polymorphic DNA PCR (RAPD-PCR) targeting the M13 sequence resulted in highly discriminatory profiles but lacked reproducibility. In this study, an MLST scheme was developed using the conserved housekeeping genes fusA, gpmA, gyrA, gyrB, lepA, pyrG, and recA, which identified 40 sequence types that successfully clustered all of the strains into the six species. Analysis of the observed alleles suggests that nucleotide substitutions within five of the seven MLST loci have reached saturation, a finding that emphasizes the highly diverse nature of the L. acidophilus complex and our unconventional application of a typically intraspecies molecular typing tool. Our MLST results indicate that this method could be useful for characterization and strain discrimination of a multispecies complex, with the potential for taxonomic expansion to a broader collection of Lactobacillus species.
    Keywords: Food Microbiology -- Methods ; Lactobacillus Acidophilus -- Classification ; Multilocus Sequence Typing -- Methods
    ISSN: 00992240
    E-ISSN: 1098-5336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: Applied and Environmental Microbiology, 01/15/2018, Vol.84(2)
    Description: High-pressure processing is a nonthermal method of food preservation that uses pressure to inactivate microorganisms. To ensure the effective validation of process parameters, it is important that the design of challenge protocols consider the potential for resistance in a particular species. Herein, the responses of 99 diverse Salmonella enterica strains to high pressure are reported. Members of this population belonged to 24 serovars and were isolated from various Canadian sources over a period of 26 years. When cells were exposed to 600 MPa for 3 min, the average reduction in cell numbers for this population was 5.6 log10 CFU/ml, with a range of 0.9 log10 CFU/ml to 6 log10 CFU/ml. Eleven strains, from 5 serovars, with variable levels of pressure resistance were selected for further study. The membrane characteristics (propidium iodide uptake during and after pressure treatment, sensitivity to membrane-active agents, and membrane fatty acid composition) and responses to stressors (heat, nutrient deprivation, desiccation, and acid) for this panel suggested potential roles for the cell membrane and the RpoS regulon in mediating pressure resistance in S. enterica The data indicate heterogeneous and multifactorial responses to high pressure that cannot be predicted for individual S. enterica strains.IMPORTANCE The responses of foodborne pathogens to increasingly popular minimal food decontamination methods are not understood and therefore are difficult to predict. This report shows that the responses of Salmonella enterica strains to high-pressure processing are diverse. The magnitude of inactivation does not depend on how closely related the strains are or where they were isolated. Moreover, strains that are resistant to high pressure do not behave similarly to other stresses, suggesting that more than one mechanism might be responsible for resistance to high pressure and the mechanisms used may vary from one strain to another.
    Keywords: Engineering ; Biology ; Economics;
    ISSN: 0099-2240
    E-ISSN: 1098-5336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: Applied and Environmental Microbiology, Dec 1, 2013, Vol.79(23), p.7220-7228
    Description: The article reports on a multilocus sequence typing (MLST) scheme developed using the preserved housekeeping genes. It was observed that nucleotide substitutions within 5 of the 7 MLST loci had reached saturation. The results revealed the importance of the MLST method for characterization and strain discrimination of a multispecies complex, with the prospects for taxonomic expansion to an extensive collection of Lactobacillus species.
    Keywords: Lactobacillus Acidophilus -- Genetic Aspects ; Lactobacillus Acidophilus -- Research ; Dna Sequencing -- Methods ; Dna Sequencing -- Research
    ISSN: 0099-2240
    ISSN: 10985336
    E-ISSN: 10985336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Applied and Environmental Microbiology, 06/15/2017, Vol.83(12)
    Description: Sequencing of single genes remains an important tool that allows the rapid classification of bacteria. Sequencing of a portion of sigB, which encodes a stress-responsive alternative sigma factor, has emerged as a commonly used molecular tool for the initial characterization of diverse Listeria isolates. In this study, evolutionary approaches were used to assess the validity of sigB allelic typing for Listeria. For a data set of 4,280 isolates, sigB allelic typing showed a Simpson's index of diversity of 0.96. Analyses of 164 sigB allelic types (ATs) found among the 6 Listeria sensu stricto species, representing these 4,280 isolates, indicate that neither frequent homologous recombination nor positive selection significantly contributed to the evolution of sigB, confirming its genetic stability. The molecular clock test provided evidence for unequal evolution rates across clades; Listeria welshimeri displayed the lowest sigB diversity and was the only species in which sigB evolved in a clocklike manner, implying a unique natural history. Among the four L. monocytogenes lineages, sigB evolution followed a molecular clock only in lineage IV. Moreover, sigB displayed a significant negative Tajima D value in lineage II, suggesting a recent population bottleneck followed by lineage expansion. The absence of positive selection along with the violation of the molecular clock suggested a nearly neutral mechanism of Listeria sensu stricto sigB evolution. While comparison with a whole-genome sequence-based phylogeny revealed that the sigB phylogeny did not correctly reflect the ancestry of L. monocytogenes lineage IV, the availability of a large sigB AT database allowed accurate species classification. IMPORTANCE sigB allelic typing has been widely used for species delineation and subtyping of Listeria. However, an informative evaluation of this method from an evolutionary perspective was missing. Our data indicate that the genetic stability of sigB is affected by neither frequent homologous recombination nor positive selection, which supports that sigB allelic typing provides reliable subtyping and classification of Listeria sensu stricto strains. However, multigene data are required for accurate phylogeny reconstruction of Listeria. This study thus contributes to a better understanding of the evolution of sigB and confirms the robustness of the sigB subtyping system for Listeria.
    Keywords: Phylogeny ; Databases ; Typing ; Classification ; Population Bottleneck ; Sigma Factor ; Homologous Recombination ; Positive Selection ; Evolution ; Listeria Welshimeri ; Listeria ; Genetics & Taxonomy ; Environmental Pollution & Waste Treatment;
    ISSN: 0099-2240
    E-ISSN: 1098-5336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: Applied and Environmental Microbiology, 07/01/2018, Vol.84(13), p.e00333-18
    Description: Of marine eubacteria, the genus is intriguing because member species are relevant to both marine ecology and human health. Many studies have touted the relationships of to environmental factors, especially temperature and salinity, to predict total abundance but lacked the taxonomic resolution to identify the relationships among species and the key drivers of dynamics. To improve next-generation sequencing (NGS) surveys of , we have conducted both 16S small subunit rRNA and heat shock protein 60 () amplicon sequencing of water samples collected at two well-studied locations in the Neuse River Estuary, NC. Samples were collected between May and December 2016 with enhanced sampling efforts in response to two named storms. Using sequences, 21 species were identified, including the potential human pathogens , , and Changes in the community mirrored seasonal and storm-related changes in the water column, especially in response to an influx of nutrient-rich freshwater to the estuary after Hurricane Matthew, which initiated dramatic changes in the overall community. Individual species dynamics were wide ranging, indicating that individual taxa have unique ecologies and that total abundance predictors are insufficient for risk assessments of potentially pathogenic species. Positive relationships between , dinoflagellates, and were identified, as were intraspecies associations, which further illuminated the interactions of cooccurring taxa along environmental gradients. The objectives of this research were to utilize a novel approach to improve sequence-based surveys of communities and to demonstrate the usefulness of this approach by presenting an analysis of dynamics in the context of environmental conditions, with a particular focus on species that cause disease in humans and on storm effects. The methods presented here enabled the analysis of dynamics with excellent taxonomic resolution and could be incorporated into future ecological studies and risk prediction strategies for potentially pathogenic species. Next-generation sequencing of and other innovative sequence-based approaches are valuable tools and show great promise for studying ecology and associated public health risks.
    Keywords: Vibrio ; Amplicon Sequencing ; Hsp60 ; Microbial Ecology ; Public Health;
    ISSN: 0099-2240
    E-ISSN: 1098-5336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: Applied and Environmental Microbiology, 06/01/2018, Vol.84(11)
    Description: The ubiquitous environmental bacterium survives and replicates within amoebae and human macrophages by forming a -containing vacuole (LCV). In an intricate process governed by the bacterial Icm/Dot type IV secretion system and a plethora of effector proteins, the nascent LCV interferes with a number of intracellular trafficking pathways, including retrograde transport from endosomes to the Golgi apparatus. Conserved retrograde trafficking components, such as the retromer coat complex or the phosphoinositide (PI) 5-phosphatase 5-phosphatase 4 (Dd5P4)/oculocerebrorenal syndrome of Lowe (OCRL), restrict intracellular replication of by an unknown mechanism. Here, we established an imaging flow cytometry (IFC) approach to assess in a rapid, unbiased, and large-scale quantitative manner the role of retrograde-linked PI metabolism and actin dynamics in the LCV composition. Exploiting genetics, we found that Dd5P4 modulates the acquisition of fluorescently labeled LCV markers, such as calnexin, the small GTPase Rab1 (but not Rab7 and Rab8), and retrograde trafficking components (Vps5, Vps26, Vps35). The actin-nucleating protein and retromer interactor WASH (Wiskott-Aldrich syndrome protein [WASP] and suppressor of cAMP receptor [SCAR] homologue) promotes the accumulation of Rab1 and Rab8 on LCVs. Collectively, our findings validate IFC for the quantitative and unbiased analysis of the pathogen vacuole composition and reveal the impact of retrograde-linked PI metabolism and actin dynamics on the LCV composition. The IFC approach employed here can be adapted for a molecular analysis of the pathogen vacuole composition of other amoeba-resistant pathogens. is an amoeba-resistant environmental bacterium which can cause a life-threatening pneumonia termed Legionnaires' disease. In order to replicate intracellularly, the opportunistic pathogen forms a protective compartment, the -containing vacuole (LCV). An in-depth analysis of the LCV composition and the complex process of pathogen vacuole formation is crucial for understanding the virulence of Here, we established an imaging flow cytometry (IFC) approach to assess in a rapid, unbiased, and quantitative manner the accumulation of fluorescently labeled markers and probes on LCVs. Using IFC and -infected or defined mutant amoebae, a role for phosphoinositide (PI) metabolism, retrograde trafficking, and the actin cytoskeleton in the LCV composition was revealed. In principle, the powerful IFC approach can be used to analyze the molecular composition of any cellular compartment harboring bacterial pathogens.
    Keywords: Dictyostelium Discoideum ; Gtpase ; Golgi Apparatus ; Legionella Pneumophila ; Ocrl ; Amoeba ; Effector Protein ; Endosome ; Host-Pathogen Interaction ; Pathogen Vacuole ; Phosphoinositide Lipid ; Retrograde Transport ; Retromer ; Sorting Nexin ; Type IV Secretion ; Vesicle Trafficking ; Host-Pathogen Interactions ; Amoeba -- Metabolism ; Dictyostelium -- Microbiology ; Legionella Pneumophila -- Pathogenicity ; Vacuoles -- Microbiology;
    ISSN: 0099-2240
    E-ISSN: 1098-5336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Language: English
    In: Applied and Environmental Microbiology, 10/15/2018, Vol.84(20)
    Description: UVC light, a strong surface disinfection technology, is used worldwide to ensure not only environmental safety but also food safety. Several drawbacks associated with the use of mercury-containing UV lamps, especially human and environmental health risks, led to the Minamata Convention on Mercury, which prohibits the manufacture and import/export of products containing mercury. Therefore, light-emitting diode (LED)-based UVC irradiation, a new technology that is ecofriendly and represents an effective UV light source, has been researched recently. To date, however, there has been no report describing pulsed UVC-LED irradiation for improvement of inactivation of foodborne pathogens, although much research regarding conventional pulsed xenon lamps has been published. In this investigation, we evaluated the enhanced bactericidal effect of a pulsed UVC-LED system, compared to continuous irradiation, and optimum conditions for maximizing the effect were determined. Also, the differences in inactivation between pulsed and continuous UVC-LED irradiation were determined by inactivation mechanism analyses. The combination of 20-Hz frequency and 50% duty ratio for pulsed UVC-LED irradiation achieved 4- to 5-log-unit reductions of O157:H7, serovar Typhimurium, and ; this combination showed the greatest bactericidal effect among various treatment conditions using 2 or 5 mJ/cm In mechanism assessments, membrane integrity (propidium iodide uptake) was not affected by UVC-LED treatment but membrane potential [bis-(1,3-dibutylbarbituric acid)trimethine oxonol [DiBAC(3)] accumulation] showed significantly different values when pulsed and continuous treatments were compared. Changes in membrane lipid peroxidation and respiratory enzyme activity were attributed to generation of more reactive oxygen species by pulsed UVC-LED irradiation. In 2013, the United Nations Environment Programme convened the Minamata Convention on Mercury, which prohibits trade in mercury-containing products in order to ensure human health. It will be effectuated in 2020; use of low-pressure mercury lamps will be discontinued and a new UV light source selected to replace the conventional technology. In this regard, UVC-LEDs have been developed and the fundamental inactivating effect has been researched. However, a pulsed UVC-LED system has not been studied, because of the difficulty of generating a UVC-LED pulse wave. An optical chopper system that physically divides the light with an adjustable blade, with personalized frequency and duty ratio settings, was introduced for generation of pulsed UVC-LED irradiation. This study elucidated the efficacy of a pulsed UVC-LED system and investigated its enhanced bactericidal effect in mechanism analyses.
    Keywords: Uv Irradiation ; Inactivating Mechanism ; Light-Emitting Diodes ; Optimization ; Pulsed Uvc-Led System ; Ultraviolet Rays ; Bacteria -- Radiation Effects ; Food Irradiation -- Methods ; Food Microbiology -- Methods ; Lighting -- Instrumentation ; Microbial Viability -- Radiation Effects;
    ISSN: 0099-2240
    E-ISSN: 1098-5336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: Applied and Environmental Microbiology, 08/15/2018, Vol.84(16)
    Description: White-nose syndrome (WNS) is an ongoing epizootic affecting multiple species of North American bats, caused by epidermal infections of the psychrophilic filamentous fungus Since its introduction from Europe, WNS has spread rapidly across eastern North America and resulted in high mortality rates in bats. At present, the mechanisms behind its spread and the extent of its adaptation to different geographic and ecological niches remain unknown. The objective of this study was to examine the geographic patterns of phenotypic variation and the potential evidence for adaptation among strains representing broad geographic locations in eastern North America. The morphological features of these strains were evaluated on artificial medium, and the viability of asexual arthroconidia of representative strains was investigated after storage at high (23°C), moderate (14°C), and low (4°C) temperatures at different lengths of time. Our analyses identified evidence for a geographic pattern of colony morphology changes among the clonal descendants of the fungus, with trait values correlated with increased distance from the epicenter of WNS. Our genomic comparisons of three representative isolates revealed novel genetic polymorphisms and suggested potential candidate mutations that might be related to some of the phenotypic changes. These results show that even though this pathogen arrived in North America only recently and reproduces asexually, there has been substantial evolution and phenotypic diversification during its rapid clonal expansion. The causal agent of white-nose syndrome in bats is , a filamentous fungus recently introduced from its native range in Europe. Infections caused by have progressed across the eastern parts of Canada and the United States over the last 10 years. It is not clear how the disease is spread, as the pathogen is unable to grow above 23°C and ambient temperature can act as a barrier when hosts disperse. Here, we explore the patterns of phenotypic diversity and the germination of the fungal asexual spores, arthroconidia, from strains across a sizeable area of the epizootic range. Our analyses revealed evidence of adaptation along geographic gradients during its expansion. The results have implications for understanding the diversification of and the limits of WNS spread in North America. Given the rapidly expanding distribution of WNS, a detailed understanding of the genetic bases for phenotypic variations in growth, reproduction, and dispersal of is urgently needed to help control this disease.
    Keywords: Adaptation ; Clonal Expansion ; Colony Size ; Fungal Pathogen ; Genome Sequencing ; Pigment Diffusion ; Pigmentation ; Spore Germination ; Cold Temperature ; Evolution, Molecular ; Acclimatization -- Genetics ; Ascomycota -- Physiology;
    ISSN: 0099-2240
    E-ISSN: 1098-5336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: Applied and Environmental Microbiology, 11/15/2017, Vol.83(22)
    Description: Carpets have been implicated in prolonged and reoccurring outbreaks of human noroviruses (HuNoV), the leading cause of acute gastroenteritis worldwide. Viral recovery from environmental surfaces, such as carpet, remains undeveloped. Our aim was to determine survival of HuNoV surrogates on an understudied environmental surface, carpet. First, we measured the zeta potential and absorption capacity of wool and nylon carpet fibers, we then developed a minispin column elution (MSC) method, and lastly we characterized the survival of HuNoV surrogates, feline calicivirus (FCV) and murine norovirus (MNV), over 60 days under 30 and 70% relative humidity (RH) on two types of carpet and one glass surface. Carpet surface charge was negative between relevant pH values (i.e., pH 7 to 9). In addition, wool could absorb approximately two times more liquid than nylon. The percent recovery efficiency obtained by the MSC method ranged from 4.34 to 20.89% and from 30.71 to 54.14% for FCV and MNV on carpet fibers, respectively, after desiccation. Overall, elution buffer type did not significantly affect recovery. Infectious FCV or MNV survived between 〈1 and 15 or between 3 and 15 days, respectively. However, MNV survived longer under some conditions and at significantly (P 〈 0.05) higher titers compared to FCV. Albeit, surrogates followed similar survival trends, i.e., both survived longest on wool then nylon and glass, while 30% RH provided a more hospitable environment compared to 70% RH. Reverse transcription-quantitative PCR signals for both surrogates were detectable for the entire study, but FCV genomic copies experienced significantly higher reductions (〈3.80 log10 copies) on all surfaces compared to MNV (〈1.10 log10 copies).IMPORTANCE Human noroviruses (HuNoV) are the leading cause of acute gastroenteritis worldwide. Classical symptoms of illness include vomiting and diarrhea which could lead to severe dehydration and death. HuNoV are transmitted by the fecal-oral or vomitus-oral route via person-to-person contact, food, water, and/or environmental surfaces. Published laboratory-controlled studies have documented the environmental stability of HuNoV on hard surfaces, but there is limited laboratory-based evidence available about survival on soft surfaces, e.g., carpet and upholstered furniture. Several epidemiological reports have suggested soft surfaces may be HuNoV fomites illustrating the importance of conducting a survival study. The three objectives of our research were to demonstrate techniques to characterize soft surfaces, develop a viral elution method for carpet, and characterize the survival of HuNoV surrogates on carpet. These results can be used to improve microbial risk assessments, the development of much-needed soft surface disinfectant, and standardizing protocols for future soft surface studies.
    Keywords: Engineering ; Biology ; Economics;
    ISSN: 0099-2240
    E-ISSN: 1098-5336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: Applied and Environmental Microbiology, 09/15/2018, Vol.84(18)
    Description: There is evidence that gut microbial signatures are indicative of host health status. However, few efforts have been devoted to establishing an applicable technique for determining disease incidence by using gut microbial signatures. Herein, we established a quantitative PCR (qPCR)-based approach to detect the relative abundances of gut disease-discriminatory phyla, which in turn afforded independent variables for quantitatively determining the incidence of shrimp disease. Given the temporal dynamics of gut bacterial communities as healthy shrimp aged, we identified disease-discriminatory phyla after ruling out age-discriminatory phyla. The top 10 disease-discriminatory phyla contributed to an overall 93.2% accuracy in diagnosis ( = 103 samples from shrimp that were determined with high confidence to be healthy or that exhibited apparent disease symptoms and subsequent death), with 70% diagnosis accuracy at the disease onset stage, when symptoms or signs of disease were not apparent. 16S rRNA gene-targeted group-specific primers of five disease-discriminatory phyla were then designed according to their compositions within shrimp gut microbiota, and other primers were borrowed from previous studies. The relative abundances of the 10 disease-discriminatory phyla assayed by qPCR exhibited a high consistency ( = 0.946, 〈 0.001) with those detected by Illumina sequencing. Notably, using the profiles of disease-discriminatory phyla assayed by qPCR and the corresponding weight coefficients as independent variables, we were able to accurately estimate the incidences of future disease outcome. This work establishes an applicable technique to quantitatively determine the incidence and onset of shrimp disease, which is a valuable attempt to translate scientific research into a practical application. Current studies have identified gut microbial signatures of host health using high-throughput sequencing (HTS) techniques. However, HTS is still expensive and time-consuming and requires a high technical ability, thereby impeding its application in routine monitoring in aquaculture. Hence, it is necessary to seek an alternative strategy to overcome these shortcomings. Herein, we establish a qPCR-based approach to detect the relative abundances of gut disease-discriminatory phyla, which in turn afford independent variables to quantitatively determine the incidence and onset of shrimp disease. Notably, there is a high consistency between the accuracies of disease diagnosis achieved by qPCR and HTS. This applicable technique makes important progress toward defining a diseased state in shrimp and toward solving an important animal health management-driven economic problem.
    Keywords: Diagnosis Accuracy ; Disease Incidence ; Disease-Discriminatory Phyla ; Independent Variable ; Shrimp Gut Microbiota ; Gastrointestinal Microbiome ; Bacteria -- Isolation & Purification ; Penaeidae -- Immunology;
    ISSN: 0099-2240
    E-ISSN: 1098-5336
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages