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821.
Isolation and characterization of coliforms from glacial ice and water in Canada's High Arctic 总被引:7,自引:0,他引:7
Ellesmere Island is the northern most member of the Canadian Arctic Archipelago with over one-third of the land mass covered by ice. A joint services expedition to the island's Blue Mountains offered a unique opportunity for microbiological studies of resident bacteria in an environment uninhabited by man. Over 100 samples of water and ice were collected from stream, lake and glacier and the filtrate cultured under canvas. Bacterial growth was harvested onto swabs for transport back to the UK and 50 coliforms chosen at random for identification and antibiotic susceptibility testing. Most of the glacial strains were capsulated, pigmented and some over 2000 years old. Genera such as Serratia, Enterobacter, Klebsiella and Yersinia were found; speciation was inconclusive and some organisms remain unidentified. Ampicillin resistance was evident in 80% of water isolates as opposed to 30% of the glacial organisms, but the isolates were generally exquisitely susceptible to antibiotics. The facility for ampicillin resistance did not appear to be transferable. Plasmid DNA was found in 33% of the glacial organisms and over 50% of the water isolates. Similar profiles were identified within and apparently between species and required plasmid restriction analysis to help establish identity. Plasmid-free Serratia spp. were subjected to genomic fingerprinting. Indistinguishable patterns were found within sets of isolates both widely spaced by distance and collection date and it was postulated that coliforms able to survive an Arctic environment had spread extensively throughout the expedition area. In conclusion, this study contributes towards knowledge of naturally occurring antibiotic resistance, confirms the presence of plasmids and genotypic data provided evidence that potentially ancient organisms from glaciers can be cultured from water samples significantly distant. 相似文献
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We propose an operational definition of spatial structure in the oceanic ecosystem; it is equivalent to the large-scale,
horizontal distribution of the dominant ecophysiological rate parameters for the questions of interest. In an important, particular
case, the relevant rate parameters are those that characterize autotrophic production. In the ocean, these parameters are
believed to be distributed in a manner that is not smoothly continuous. Rather, they seem to have a piecewise continuous distribution.
This leads to a requirement to partition the ocean into a suite of provinces where the boundaries between the provinces mark
the locations of abrupt changes in the magnitudes of the rate parameters. The area covered by a particular province represents
an area of common physical forcing, insofar as the forcing is relevant to autotrophic production. The boundaries are taken
to be elastic rather than fixed, such that they can respond to variations in forcing. At any given time, the boundaries can
be located with the aid of remotely sensed imagery, especially ocean-color imagery.
Received 7 January 1999; accepted 2 June 1999. 相似文献
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