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  • Springer  (2)
  • The American Society for Microbiology (ASM)  (1)
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  • 1
    Publication Date: 2019-09-23
    Description: The oxidation of ammonia plays a significant role in the transformation of fixed nitrogen in the global nitrogen cycle. Autotrophic ammonia oxidation is known in three groups of microorganisms. Aerobic ammonia-oxidizing bacteria and archaea convert ammonia into nitrite during nitrification. Anaerobic ammonia-oxidizing bacteria (anammox) oxidize ammonia using nitrite as electron acceptor and producing atmospheric dinitrogen. The isolation and cultivation of all three groups in the laboratory are quite problematic due to their slow growth rates, poor growth yields, unpredictable lag phases, and sensitivity to certain organic compounds. Culture-independent approaches have contributed importantly to our understanding of the diversity and distribution of these microorganisms in the environment. In this review, we present an overview of approaches that have been used for the molecular study of ammonia oxidizers and discuss their application in different environments.
    Type: Article , PeerReviewed
    Format: text
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  • 2
    Publication Date: 2019-09-23
    Description: The genes and intergenic regions of the amoCAB operon were analyzed to establish their potential as molecular markers for analyzing ammonia-oxidizing betaproteobacterial (beta-AOB) communities. Initially, sequence similarity for related taxa, evolutionary rates from linear regressions, and the presence of conserved and variable regions were analyzed for all available sequences of the complete amoCAB operon. The gene amoB showed the highest sequence variability of the three amo genes, suggesting that it might be a better molecular marker than the most frequently used amoA to resolve closely related AOB species. To test the suitability of using the amoCAB genes for community studies, a strategy involving nested PCR was employed. Primers to amplify the whole amoCAB operon and each individual gene were tested. The specificity of the products generated was analyzed by denaturing gradient gel electrophoresis, cloning, and sequencing. The fragments obtained showed different grades of sequence identity to amoCAB sequences in the GenBank database. The nested PCR approach provides a possibility to increase the sensitivity of detection of amo genes in samples with low abundance of AOB. It also allows the amplification of the almost complete amoA gene, with about 300 bp more sequence information than the previous approaches. The coupled study of all three amo genes and the intergenic spacer regions that are under different selection pressure might allow a more detailed analysis of the evolutionary processes, which are responsible for the differentiation of AOB communities in different habitats.
    Type: Article , PeerReviewed
    Format: text
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  • 3
    Publication Date: 2013-08-08
    Description: Bacterial endospores are highly specialized cellular forms that allow endospore-forming Firmicutes (EFF) to tolerate harsh environmental conditions. EFF are considered ubiquitous in natural environments, in particular, those subjected to stress conditions. In addition to natural habitats, EFF are often the cause of contamination problems in anthropogenic environments, such as industrial production plants or hospitals. It is therefore desirable to assess their prevalence in environmental and industrial fields. To this end, a high-sensitivity detection method is still needed. The aim of this study was to develop and evaluate an approach based on quantitative PCR (qPCR). For this, the suitability of functional genes specific for and common to all EFF were evaluated. Seven genes were considered, but only spo0A was retained to identify conserved regions for qPCR primer design. An approach based on multivariate analysis was developed for primer design. Two primer sets were obtained and evaluated with 16 pure cultures, including representatives of the genera Bacillus , Paenibacillus , Brevibacillus , Geobacillus , Alicyclobacillus , Sulfobacillus , Clostridium , and Desulfotomaculum , as well as with environmental samples. The primer sets developed gave a reliable quantification when tested on laboratory strains, with the exception of Sulfobacillus and Desulfotomaculum . A test using sediment samples with a diverse EFF community also gave a reliable quantification compared to 16S rRNA gene pyrosequencing. A detection limit of about 10 4 cells (or spores) per gram of initial material was calculated, indicating this method has a promising potential for the detection of EFF over a wide range of applications.
    Print ISSN: 0099-2240
    Electronic ISSN: 1098-5336
    Topics: Biology
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