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  • 1
    Electronic Resource
    Electronic Resource
    Prevalence of streptomycin-resistance genes in bacterial populations in European habitats (2002)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 42 (2002), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The prevalence of selected streptomycin (Sm)-resistance genes, i.e. aph (3″), aph (6)-1d, aph (6)-1c, ant (3″) and ant (6), was assessed in a range of pristine as well as polluted European habitats. These habitats included bulk and rhizosphere soils, manure from farm animals, activated sludge from wastewater treatment plants and seawater. The methods employed included assessments of the prevalence of the genes in habitat-extracted DNA by PCR, followed by hybridisation with specific probes, Sm-resistant culturable bacteria and exogenous isolation of plasmids carrying Sm-resistance determinants. The direct DNA-based analysis showed that aph (6)-1d genes were most prevalent in the habitats examined. The presence of the other four Sm-modifying genes was demonstrated in 58% of the tested habitats. A small fraction of the bacterial isolates (8%) did not possess any of the selected Sm-modifying genes. These isolates were primarily obtained from activated sludge and manure. The presence of Sm-modifying genes in the isolates often coincided with the presence of IncP plasmids. Exogenous isolation demonstrated the presence of plasmids of 40–200 kb in size harbouring Sm-resistance genes from all the environments tested. Most plasmids were shown to carry the ant (3″) gene, often in combination with other Sm-resistance genes, such as aph (3″) and aph (6)-1d. The most commonly found Sm-modifying gene on mobile genetic elements was ant (3″). Multiple Sm-resistance genes on the same genetic elements appeared to be the rule rather than the exception. It is concluded that Sm-resistance genes are widespread in the environmental habitats studied and often occur on mobile genetic elements and ant (3″) was most often encountered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.2002.tb01018.x
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  • 2
    Electronic Resource
    Electronic Resource
    PCR typing of tetracycline resistance determinants (Tet A–E) in Salmonella enterica serotype Hadar and in the microbial community of activated sludges from hospital and urban wastewater treatment facilities in Belgium (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 32 (2000), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The distribution of tetracycline resistance determinants Tet A–E was studied by PCR in 40 tetracycline-resistant Salmonella enterica serotype Hadar (S. hadar) isolates collected from human patients in 1996 and 1997, as well as in the microbial community originating from activated sludges of hospital and urban wastewater treatment facilities. A fast DNA extraction and purification method from activated sludges was used to provide amplifiable DNA. The method is based on the direct lysis of bacteria improved by bead-beating followed by DNA purification on polyvinylpolypyrrolidone spin columns to remove PCR inhibitors. The purified DNAs from salmonellae and activated sludges were characterized for the presence of tetracycline determinants with specific primer pairs designed on the basis of published sequences. The Tet A determinant was present in all clinical isolates and DNAs extracted from the bacterial community of the selected activated sludges. The Tet C determinant was identified in only one of the 40 clinical isolates and in six of the seven environmental samples. No signal was detected for Tet B, D and E determinants. This study revealed a high and stable prevalence of the Tet A determinant in both salmonellae clinical isolates and the microbial community of activated sludges from hospital and urban wastewater treatment facilities over a 2-year period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.2000.tb00701.x
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  • 3
    Electronic Resource
    Electronic Resource
    Retromobilization of heavy metal resistance genes in unpolluted and heavy metal polluted soil (1995)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 18 (1995), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: Retromobilization of the nonconjugative (Tra−Mob+) IncQ vector, pMOL155, and the non-mobilizable (Tra−Mob−) vector, pMOL149, by means of the IncP plasmids RP4 and pULB113 (RP4::Mu3A), was studied in plate matings and in soil microcosms, and compared with direct and triparental mobilization. Both vectors harbour the czc genes, originating from Alcaligenes eutrophus, which code for resistance to Co, Zn, and Cd. The donor of the czc genes was Escherichia coli which did not express these genes. The recipient, Alcaligenes eutrophus, expressed the czc genes very well. Retromobilization, direct and triparental mobilization of pMOL155 was observed in sterile soil. Both the addition of nutrients and heavy metals significantly enhanced the number of (retro)transconjugants. Retromobilization was also detected in nutrient amended nonsterile soil, but the presence of the autochthonous soil biota strongly reduced the number of retrotransconjugants and also prevented their increase upon application of heavy metals to the soil. Retromobilization of the czc genes, cloned in pMOL149, by using pULB113 was also observed, yet only in sterile, nutrient amended, heavy metal polluted soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.1995.tb00176.x
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    Paper (German National Licenses)
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