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 Please tell us about your educational background and early research experiences.

I studied microbiology at the University of Innsbruck (Austria), where I am now Associate Professor of Microbiology at the Institute of Microbiology. My research interests include low-temperature bioremediation of alpine soils contaminated with hydrocarbons and polyphasic characterization of psychrophilic microorganisms in alpine environments (glaciers and soils).

 What first drew your interest to oil spill remediation?

"Our data demonstrated that soil biology measurements are sensitive to contamination."

I had already started working with cold-adapted microorganisms during my Ph.D. studies. After my Ph.D., I worked as a postdoc in a bioremediation project and focused on low-temperature bioremediation in the alpine environment.

 One of your highly cited papers in our analysis is the 2003 Applied and Environmental Microbiology article, "Characterization of hydrocarbon-degrading microbial populations in contaminated and pristine alpine soils" (Margesin R, et al., 69[6]: 3085-92, June 2003). Would you please tell us about this paper—your methods and findings, and the implications for the field?

This paper was produced in cooperation with Canadian partners (Lyle G. Whyte from McGill University, and Charles W. Greer from NRC, Biotechnology Research Institute, Montreal). The aim of the study was to characterize microorganisms involved in the degradation of petroleum hydrocarbons in alpine soils by using molecular methods. We investigated the prevalence of seven genotypes involved in the degradation of n-alkanes, aromatic hydrocarbons, and polycyclic aromatic hydrocarbons in petroleum-hydrocarbon-contaminated and pristine alpine soils from Tyrol (Austria).

Genotypes containing genes from Gram-negative bacteria were detected to a significantly higher percentage in the contaminated than in the pristine soils, indicating these organisms had been enriched in alpine soils following contamination. Consequently, a highly significant positive correlation between the petroleum hydrocarbon content and the number of genotypes containing genes from Gram-negative bacteria, such as Pseudomonas sp. and Acinetobacter sp., was found.

In contrast, no significant correlation between the total petroleum hydrocarbon content and the number of genotypes containing genes from Gram-positive bacteria (such as Rhodococcus sp. and Mycobacterium sp.) could be detected. These genotypes were detected at a high frequency both in contaminated and pristine soils, indicating they are already present in substantial numbers in alpine soils before a contamination event.

The results of this and similar other studies contributed to a better understanding of the indigenous biodegradation potential in soils of cold regions. Further studies with the Canadian groups focused on microbial diversity in contaminated and pristine alpine soils.

 Earlier this year, your group published a paper in Environmental Monitoring and Assessment: "Ecotoxicological and microbiological characterization of soils from heavy-metal- and hydrocarbon-contaminated sites" (Plaza GA, et al., 163[1-4]: 477-88, April 2010). Please sum this research up for our readers.

This paper was produced in cooperation with Polish partners (Institute for Ecology of Industrial Areas, Katowice, and Medical University of Warsaw). The aim of this study was to characterize soils from long-term contaminated industrial sites located in the Upper Silesia Industrial Region in southern Poland. The soils contained high amounts of heavy metals or petroleum hydrocarbons. We combined physicochemical, microbiological, and ecotoxicological parameters and assessed the suitability of these assays for the evaluation of contaminated sites.

Soil microbiological properties revealed the presence of high numbers of culturable heterotrophic microorganisms. Our data demonstrated that soil biology measurements are sensitive to contamination. Soil enzyme activities were considerably reduced or could not be detected in contaminated soils.

"The results of this and similar other studies contributed to a better understanding of the indigenous biodegradation potential in soils of cold regions."

Activities involved in nitrogen turnover (N mineralization and nitrification) were significantly higher in soils from the metal-contaminated sites than in samples from the hydrocarbon-contaminated site, whereas the opposite was observed for phosphatase activity. Correlation analysis between principal components determined for physicochemical, microbiological, and ecotoxicological soil properties demonstrated the impact of total and water-soluble contents of heavy metals on toxicity. Recent studies on these soils focused on microbial community composition.

 How far has bioremediation come in the past decade? Where do you hope to take it in the future?

The capacity of a broad spectrum of microorganisms to utilize hydrocarbons as the sole source of carbon and energy has been recognized already by ZoBell in 1946 and was the basis for the development of biological remediation methods. Bioremediation attempts to accelerate the natural biodegradation rates through the optimization of limiting environmental conditions and is an ecologically and economically effective method.

With regard to bioremediation in cold climates (my research topic), evidence for the biodegradation activity of indigenous microorganisms in contaminated cold environments has been provided by high numbers and activities of hydrocarbon degraders, the prevalence of genotypes with catabolic pathways for the degradation of a wide range of hydrocarbons, and high mineralization potentials.

Several remediation schemes have been implemented successfully at petroleum-contaminated sites in the Arctic during the past decade. Engineered bioremediation allows us to remediate large volumes of petroleum-contaminated soils to cleanup standards within 2-3 treatment seasons in Alaska and to lengthen the usual short Arctic bioremediation season from May to November (see Filler et al., 2008).

However, low-temperature bioremediation also has its limits, which include an acceptable cleanup performance within an acceptable time frame. By using bioremediation, a contamination cannot be reduced to zero, especially in soils with aged contamination. It will be a challenge for the next years to overcome these limits.

Successful bioremediation requires in situ studies of the behavior of microbial communities during bioremediation and the development of efficient methods that can be applied in situ to monitor bioremediation. However, each soil to be treated has its own contamination history and therefore it will not be possible to develop a generally applicable bioremediation protocol.

Rosa Margesin, Ph.D.
Institute of Microbiology
University of Innsbruck
Innsbruck, Austria

KEYWORDS: BIOREMEDIATION, ALPINE SOILS, CONTAMINATION, HYDROCARBONS, N-ALKANES, GRAM-NEGATIVE, GRAM-POSITIVE, PSEUDOMONAS SP, ACINETOBACTER SP, RHODOCOCCUS SP, MYCOBACTERIUM SP, CONTAMINATED SOILS, PRISTINE SOILS, SOIL MICROBIOLOGICAL PROPERTIES, CULTURABLE HETROTROPHIC MICROORGANISMS, SOIL ENZYME ACTIVITIES, NITROGEN TURNOVER, PHOSPHATASE ACTIVITY, MICROBIAL COMMUNITY COMPOSITION, BIODEGRADATION, GENOTYPES, CATABOLIC PATHWAYS, TIME FRAME, IN SITU STUDIES.

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