Microarray and Real-Time PCR Analyses of the Responses of
High-Arctic Soil Bacteria to Hydrocarbon Pollution and
Etienne Yergeau,1,2 Me´lanie Arbour,1 Roland Brousseau,1 David Juck,1 John R. Lawrence,3 Luke Masson,1 Lyle G. Whyte,2 and Charles W. Greer1*
Institute, 6100 Royalmount Ave., Montre´al H4P 2R2, QC,
High-Arctic soils have low nutrient availability, low moisture content, and very low temperatures and, as
such, they pose a particular problem in terms of hydrocarbon bioremediation. An in-depth knowledge of the
microbiology involved in this process is likely to be crucial to understand and optimize the factors most
influencing bioremediation. Here, we compared two distinct large-scale field bioremediation experiments,
located at the Canadian high-Arctic stations of Alert (ex situ approach) and Eureka (in situ approach).
Bacterial community structure and function were assessed using microarrays targeting the 16S rRNA genes of
bacteria found in cold environments and hydrocarbon degradation genes as well as quantitative reverse
transcriptase PCR targeting key functional genes. The results indicated a large difference between sampling
sites in terms of both soil microbiology and decontamination rates. A rapid reorganization of the bacterial
community structure and functional potential as well as rapid increases in the expression of alkane monooxygenases
and polyaromatic hydrocarbon-ring-hydroxylating dioxygenases were observed 1 month after the
bioremediation treatment commenced in the Alert soils. In contrast, no clear changes in community structure
were observed in Eureka soils, while key gene expression increased after a relatively long lag period (1 year).
Such discrepancies are likely caused by differences in bioremediation treatments (i.e., ex situ versus in situ),
weathering of the hydrocarbons, indigenous microbial communities, and environmental factors such as soil
humidity and temperature. In addition, this study demonstrates the value of molecular tools for the monitoring
of polar bacteria and their associated functions during bioremediation.
Keywords:Rhodococcus,Pseudomonas,Sphingomonas, soil microbiology,hydrocarbon bioremediation,bioremediation.
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