Sandra Dworatzek and Jennifer Webb (ON), coauthored a paper entitled “Anaerobic Benzene Biodegradation Linked to Growth of Highly Specific Bacterial Clades” accepted for publication in Environmental Science & Technology.

Courtney Toth, Ph.D. & Fei Luo (Department of Chemical Engineering and Applied Chemistry, University of Toronto) were the lead authors and their coauthors in addition to Sandra and Jennifer included Nancy Bawa, Shen Guo and Prof. Elizabeth Edwards, Ph.D., O.C. (Department of Chemical Engineering and Applied Chemistry, University of Toronto).

Sandra is a Principal Scientist with more than 25 years of experience in bioremediation of chlorinated solvents, petroleum hydrocarbons, emerging contaminants and other recalcitrant compounds. She has specific technical experience in the design of laboratory treatability studies, the scale up of growth of aerobic and anaerobic microbial cultures for bioaugmentation laboratory and field pilot tests, and evaluation of aerobic and anaerobic bioremediation, zero valent iron and chemical oxidation technologies in the laboratory. She currently provides senior technical oversight of laboratory treatability studies and the development and scaleup of new bioaugmentation cultures, including novel cultures for BTEX compounds under anaerobic conditions and aerobic 1,4-dioxane bioremediation. Sandra currently is the industry lead on a Genome Canada funded project for the commercialization of anaerobic BTEX degrading cultures.

Jennifer is the Research Coordinator at SiREM with more than 17 years of experience in microbiology where she develops new cultures while coordinating R&D collaborations with researchers globally.

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Published Abstract

Reliance on bioremediation to remove benzene from anoxic environments has proven risky for decades but for unknown reasons. Years of research have revealed a strong link between anaerobic benzene biodegradation and the enrichment of highly specific microbes, namely Thermincola in the family Peptococcaceae and the deltaproteobacterial Candidate Sva0485 clade. Using aquifer material from Canadian Forces Base Borden, we compared five bioremediation approaches in batch microcosms. Under conditions simulating natural attenuation or sulfate biostimulation, benzene was not degraded after 1-2 years of incubation and no enrichment of known benzene degrading microbes occurred. In contrast, nitrate-amended microcosms reported benzene biodegradation coincident with significant growth of Thermincola spp., along with a functional gene presumed to catalyze anaerobic benzene carboxylation (abcA). Inoculation with 2.5% of a methanogenic benzene-degrading consortium containing Sva0485 (Deltaproteobacteria ORM2) resulted in benzene biodegradation in the presence of sulfate or under methanogenic conditions. The presence of other hydrocarbon co-contaminants decreased rates of benzene degradation by a factor of 2-4. Tracking the abundance of the abcA gene and 16S rRNA genes specific for benzene degrading Thermincola and Sva0485 is recommended to monitor benzene bioremediation in anoxic groundwater systems to further uncover growth rate limiting conditions for these two intriguing phylotypes.

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