1,4-Dioxane

A low carbon isotope enrichment factor of -1.73‰ was reported during the aerobic metabolism of 1,4-dioxane by Pseudonocardia dioxanivorans CB1190 (Pornwongthong et al. 2011). However, compound specific isotope analysis (CSIA) may ultimately be a useful monitoring tool when assessing aerobic dioxane biodegradation. Although continued research is needed, early laboratory studies suggest that dioxane biodegradation may lead to notable hydrogen isotope enrichment.

Consider Stable Isotope Probing:  Stable isotope probing (SIP) is an innovative method to track the environmental fate of a 13C “labeled” contaminant like benzene to conclusively determine if biodegradation is occurring.  The 13C label serves much like a tracer.  If biodegradation is occurring the 13C label will be detected in the end products of biodegradation – biomass and dissolved inorganic carbon (CO2).  CSIA on the other hand is based on analysis of the 13C/12C ratio of the contaminant itself.

Also Consider CENSUS qPCR:  CSIA can be performed in conjunction with qPCR to quantify functional genes involved in the aerobic metabolism and cometabolism of dioxane.   In aerobic dioxane utilizing bacterium Pseudonocardia dioxanivorans CB1190, the first step in dioxane metabolism is mediated by a dioxane/tetrahydrofuran monooxygenase (DXMO/THFMO).  Microbial Insights also offers qPCR assays to quantify functional genes encoding enzymes capable of dioxane cometabolism including propane monooxygenase (PPO) and aromatic monooxygenases (RMO, RDEG).

References

Gedalanga, P.B., P. Pornwongthong, R. Mora, S.-Y.D. Chiang, B. Baldwin, D. Ogles, and S. Mahendra. 2014. Identification of Biomarker Genes To Predict Biodegradation of 1,4-Dioxane. Applied and Environmental Microbiology 80 no. 10: 3209-3218.

Lan, R.S., C.A. Smith, and M.R. Hyman. 2013. Oxidation of Cyclic Ethers by Alkane-Grown Mycobacterium vaccae JOB5. Remediation Journal 23 no. 4: 23-42.

Mahendra, S., and L. Alvarez-Cohen. 2006. Kinetics of 1,4-Dioxane Biodegradation by Monooxygenase-Expressing Bacteria. Environmental Science & Technology 40 no. 17: 5435-5442.

Mahendra, S., C.J. Petzold, E.E. Baidoo, J.D. Keasling, and L. Alvarez-Cohen. 2007. Identification of the Intermediates of in Vivo Oxidation of 1,4-Dioxane by Monooxygenase-Containing Bacteria. Environmental Science & Technology 41 no. 21: 7330-7336.

Masuda, H., K. McClay, R.J. Steffan, and G.J. Zylstra. 2012. Biodegradation of Tetrahydrofuran and 1,4-Dioxane by Soluble Diiron Monooxygenase in <b><i>Pseudonocardia</i></b> sp. Strain ENV478. Journal of Molecular Microbiology and Biotechnology 22 no. 5: 312-316.

Pornwongthong, P., G.L. Paradis, and S. Mahendra. 2011. Stable Carbon Isotope Fractionation During 1,4-Dioxane Biodegradation. Proceedings of the Water Environment Federation 2011 no. 18: 111-116.

Vainberg, S., K. McClay, H. Masuda, D. Root, C. Condee, G.J. Zylstra, and R.J. Steffan. 2006. Biodegradation of Ether Pollutants by Pseudonocardia sp. Strain ENV478. Applied and Environmental Microbiology 72 no. 8: 5218-5224.