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  • 1
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 76, No. 15 ( 2010-08), p. 5046-5057
    Kurzfassung: The genetic manageability of the biotechnologically important Bacillus licheniformis is hampered due to its poor transformability, whereas Bacillus subtilis efficiently takes up DNA during genetic competence, a quorum-sensing-dependent process. Since the sensor histidine kinase ComP, encoded by a gene of the quorum-sensing module comQXPA of B. licheniformis DSM13, was found to be inactive due to an insertion element within comP , the coding region was exchanged with a functional copy. Quorum sensing was restored, but the already-poor genetic competence dropped further. The inducible expression of the key regulator for the transcription of competence genes, ComK, in trans resulted in highly competent strains and facilitated the direct disruption of genes, as well as the conditional knockout of an essential operon. As ComK is inhibited at low cell densities by a proteolytic complex in which MecA binds ComK and such inhibition is antagonized by the interaction of MecA with ComS (the expression of the latter is controlled by cell density in B. subtilis ), we performed an in silico analysis of MecA and the hitherto unidentified ComS, which revealed differences for competent and noncompetent strains, indicating that the reduced competence possibly is due to a nonfunctional coupling of the comQXPA -encoded quorum module and ComK. The obtained increased genetic tractability of this industrial workhorse should improve a wide array of scientific investigations.
    Materialart: Online-Ressource
    ISSN: 0099-2240 , 1098-5336
    RVK:
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2010
    ZDB Id: 223011-2
    ZDB Id: 1478346-0
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Online-Ressource
    Online-Ressource
    Springer Science and Business Media LLC ; 2015
    In:  Applied Microbiology and Biotechnology Vol. 99, No. 5 ( 2015-3), p. 2255-2266
    In: Applied Microbiology and Biotechnology, Springer Science and Business Media LLC, Vol. 99, No. 5 ( 2015-3), p. 2255-2266
    Materialart: Online-Ressource
    ISSN: 0175-7598 , 1432-0614
    RVK:
    Sprache: Englisch
    Verlag: Springer Science and Business Media LLC
    Publikationsdatum: 2015
    ZDB Id: 1464336-4
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 76, No. 24 ( 2010-12-15), p. 8211-8221
    Kurzfassung: By targeted deletion of the polyglutamate operon ( pga ) in Bacillus licheniformis F11, a derivative form, F11.1 (Δ pga ), was obtained that, along with lacking polyglutamate (PGA) formation, displayed enhanced proteolytic activities. The phenotypic properties were maintained in a strain in which the chiBA operon was additionally deleted: F11.4 (Δ chiBA Δ pga ). These genetically modified strains, carrying the Δ pga deletion either alone (F11.1) or together with the Δ chiBA (F11.4) deletion, were used in fermentations (20-liter scale) aiming at the deproteinization of shrimp shells in order to obtain long-chain chitin. After chemical deacetylation, the resulting chitosan samples were analyzed by nuclear magnetic resonance spectroscopy, size exclusion chromatography, and viscometry and compared to a chitosan preparation that was produced in parallel by chemical methods by a commercial chitosan supplier (GSRmbH). Though faint lipid impurities were present in the fermented polysaccharides, the viscosity of the material produced with the double-deletion mutant F11.4 (Δ pga Δ chiBA ) was higher than that of the chemically produced and commercially available samples (Cognis GmbH). Thus, enhanced proteolytic activities and a lack of chitinase activity render the double mutant F11.4 a powerful tool for the production of long-chain chitosan.
    Materialart: Online-Ressource
    ISSN: 0099-2240 , 1098-5336
    RVK:
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2010
    ZDB Id: 223011-2
    ZDB Id: 1478346-0
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    In: Microbiology, Microbiology Society, Vol. 160, No. 10 ( 2014-10-01), p. 2136-2147
    Kurzfassung: Bacterial natural genetic competence – well studied in Bacillus subtilis – enables cells to take up and integrate extracellularly supplied DNA into their own genome. However, little is known about competence development and its regulation in other members of the genus, although DNA uptake machineries are routinely encoded. Auxotrophic Bacillus licheniformis 9945A derivatives, obtained from repeated rounds of random mutagenesis, were long known to develop natural competence. Inspection of the colony morphology and extracellular enzyme secretion of two of these derivatives, M28 and M18, suggested that regulator genes are collaterally hit. M28 emerged as a 14 bp deletion mutant concomitantly displaying a shift in the reading frame of degS that encodes the sensor histidine kinase, which is part of the molecular switch that directs cells to genetic competence, the synthesis of extracellular enzymes or biofilm formation, while for M18, sequencing of the suspected gene revealed a 375 bp deletion in abrB , encoding the major transition state regulator. With respect to colony morphology, enzyme secretion and competence development, both of the mutations, when newly generated on the wild-type B. licheniformis 9945A genetic background, resulted in phenotypes resembling M28 and M18, respectively. All of the known naturally competent B. licheniformis representatives, hitherto thoroughly investigated in this regard, carry mutations in regulator genes, and hence genetic competence observed in domesticated strains supposedly results from deregulation.
    Materialart: Online-Ressource
    ISSN: 1350-0872 , 1465-2080
    Sprache: Englisch
    Verlag: Microbiology Society
    Publikationsdatum: 2014
    ZDB Id: 2008736-6
    SSG: 12
    Standort Signatur Einschränkungen Verfügbarkeit
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