Biodegradation - 1,4-Dioxane - Revision history

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 *[[1,4-Dioxane]]
 *[[Biodegradation - Cometabolic]]
 '''Contributor(s):''' [[Dr. Shaily Mahendra]] and [[Dr. Michael Hyman]]
 '''Key Resource(s)''':

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 | ''Pseudomonas mendocina'' KR1 || T4MO || 0.37± 0.04 mg/hr/mg-protein || Mahendra and Alvarez-Cohen (2006)<ref name= "Mahendra2006"/>
 |-
-| ''Aureobasidium pullmans'' NRRL 21064 || ? || 6-8 mg/L within a day || Patt and Abebe (1995)<ref name= "Patt1995">Patt, T.E. and Abebe, H.M., Upjohn Co, 1995. Microbial degradation of chemical pollutants. U.S. Patent 5,399,495. [[media:1995-Patt-Microbial_degradation_of_chemical_pollutants.pdf| Patent.pdf]]</ref>
+| ''Aureobasidium pullmans'' NRRL 21064 || ? || 6-8 mg/L within a day || Patt and Abebe (1995)<ref name= "Patt1995">Patt, T.E. and Abebe, H.M., Upjohn Co, 1995. Microbial degradation of chemical pollutants. U.S. Patent 5,399,495. [[media:1995-Patt-Microbial_degradation_of_chemical_pollutants.pdf| Patent pdf]]</ref>
 |-
 | ''Graphium'' sp. ATCC 58400 (fungus) || CYP || 4 ± 1 nmol/min/mg dry weight (with Propane) <br/>9 ± 5 nmol/min/mg dry weight (with THF) || Skinner et al. (2009)<ref name= "Skinner2009">Skinner, K., Cuiffetti, L. and Hyman, M., 2009. Metabolism and cometabolism of cyclic ethers by a filamentous fungus, a Graphium sp. Appl. Environ. Microbiol., 75(17), pp.5514-5522. [https://doi.org/10.1128/aem.00078-09 doi:10.1128/AEM.00078-09] [[media:Skinner2009.pdf| Article pdf]]</ref>

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 | ''Pseudonocardia dioxanivorans'' CB1190 || THFMO || 0.19 ± 0.007 mg/hr/mg-protein || Mahendra and Alvarez-Cohen (2005, 2006)<ref name= "Mahendra2005">Mahendra, S. and Alvarez-Cohen, L., 2005. Pseudonocardia dioxanivorans sp. nov., a novel actinomycete that grows on 1, 4-dioxane. International Journal of Systematic and Evolutionary Microbiology, 55(2), pp.593-598. [https://doi.org/10.1099/ijs.0.63085-0 doi: 10.1099/ijs.0.63085-0]</ref><ref name= "Mahendra2006"/>
 |-
-| ''Actinomycete'' CB1190* || N/A || 0.33 mg/min/mg-protein || Parales et al. (1994)<ref name= "Parales1994">Parales, R.E., Adamus, J.E., White, N. and May, H.D., 1994. Degradation of 1, 4-dioxane by an actinomycete in pure culture. Applied and Environmental Microbiology, 60(12), pp.4527-4530. [https://doi.org/10.1128/aem.60.12.4527-4530.1994 doi:10.1128/aem.60.12.4527-4530.1994] [[media:1994-Parales-Degradation_of_1%2C4-Dioxane_by_an_Actinomycete_in_Pure_Culture.pdf| Article.pdf]]</ref>
+| ''Actinomycete'' CB1190* || N/A || 0.33 mg/min/mg-protein || Parales et al. (1994)<ref name= "Parales1994">Parales, R.E., Adamus, J.E., White, N. and May, H.D., 1994. Degradation of 1, 4-dioxane by an actinomycete in pure culture. Applied and Environmental Microbiology, 60(12), pp.4527-4530. [https://doi.org/10.1128/aem.60.12.4527-4530.1994 doi:10.1128/aem.60.12.4527-4530.1994] [[media:1994-Parales-Degradation_of_1%2C4-Dioxane_by_an_Actinomycete_in_Pure_Culture.pdf| Article pdf]]</ref>
 |-
 | ''Amycolata'' sp. CB1190* || N/A || 0.038 ± 0.012 mg/hr/mg-protein || Kelley et al. (2001)
@@ Line 49: / Line 49: @@
 | ''Mycobacterium austroafricanum'' JOB5 || ? || 0.40 ± 0.06 mg/hr/mg-protein || House and Hyman (2010)<ref>House, A.J. and Hyman, M.R., 2010. Effects of gasoline components on MTBE and TBA cometabolism by Mycobacterium austroafricanum JOB5. Biodegradation, 21(4), pp.525-541. [https://doi.org/10.1007/s10532-009-9321-8 doi: 10.1007/s10532-009-9321-8]</ref>, Lan et al. (2013)<ref>Lan, R.S., Smith, C.A. and Hyman, M.R., 2013. Oxidation of cyclic ethers by alkane‐grown Mycobacterium vaccae JOB5. Remediation Journal, 23(4), pp.23-42. [https://doi.org/10.1002/rem.21364 doi: 10.1002/rem.21364]</ref><ref name= "Mahendra2006"/>
 |-
-| ''Rhodococcus ruber'' ENV425 || ? || 10 mg/hr/g TSS || Lippincott et al. (2015)<ref name= "Lippincott2015">Lippincott, D., Streger, S.H., Schaefer, C.E., Hinkle, J., Stormo, J. and Steffan, R.J., 2015. Bioaugmentation and propane biosparging for in situ biodegradation of 1, 4‐dioxane. Groundwater Monitoring & Remediation, 35(2), pp.81-92. [https://doi.org/10.1111/gwmr.12093 doi: 10.1111/gwmr.12093]</ref>, Vainberg et al. (2006)<ref name= "Vainberg2006">Vainberg, S., McClay, K., Masuda, H., Root, D., Condee, C., Zylstra, G.J. and Steffan, R.J., 2006. Biodegradation of ether pollutants by Pseudonocardia sp. strain ENV478. Appl. Environ. Microbiol., 72(8), pp.5218-5224. [https://doi.org/10.1128/aem.00160-06 doi: 10.1128/AEM.00160-06] [[media:Vainberg2006.pdf| Article.pdf]]</ref>
+| ''Rhodococcus ruber'' ENV425 || ? || 10 mg/hr/g TSS || Lippincott et al. (2015)<ref name= "Lippincott2015">Lippincott, D., Streger, S.H., Schaefer, C.E., Hinkle, J., Stormo, J. and Steffan, R.J., 2015. Bioaugmentation and propane biosparging for in situ biodegradation of 1, 4‐dioxane. Groundwater Monitoring & Remediation, 35(2), pp.81-92. [https://doi.org/10.1111/gwmr.12093 doi: 10.1111/gwmr.12093]</ref>, Vainberg et al. (2006)<ref name= "Vainberg2006">Vainberg, S., McClay, K., Masuda, H., Root, D., Condee, C., Zylstra, G.J. and Steffan, R.J., 2006. Biodegradation of ether pollutants by Pseudonocardia sp. strain ENV478. Appl. Environ. Microbiol., 72(8), pp.5218-5224. [https://doi.org/10.1128/aem.00160-06 doi: 10.1128/AEM.00160-06] [[media:Vainberg2006.pdf| Article pdf]]</ref>
 |-
 | ''Pseudonocardia'' sp. ENV478 || THFMO || 21 mg/hr/g TSS || Masuda et al. (2012)<ref>Masuda, H., McClay, K., Steffan, R.J. and Zylstra, G.J., 2012. Biodegradation of tetrahydrofuran and 1, 4-dioxane by soluble diiron monooxygenase in Pseudonocardia sp. strain ENV478. Journal of Molecular Microbiology and Biotechnology, 22(5), pp.312-316. [https://doi.org/10.1159/000343817  doi: 10.1159/000343817]</ref>, Vainberg et al. (2006)<ref name= "Vainberg2006"/>
@@ Line 69: / Line 69: @@
 | ''Aureobasidium pullmans'' NRRL 21064 || ? || 6-8 mg/L within a day || Patt and Abebe (1995)<ref name= "Patt1995">Patt, T.E. and Abebe, H.M., Upjohn Co, 1995. Microbial degradation of chemical pollutants. U.S. Patent 5,399,495. [[media:1995-Patt-Microbial_degradation_of_chemical_pollutants.pdf| Patent.pdf]]</ref>
 |-
-| ''Graphium'' sp. ATCC 58400 (fungus) || CYP || 4 ± 1 nmol/min/mg dry weight (with Propane) <br/>9 ± 5 nmol/min/mg dry weight (with THF) || Skinner et al. (2009)<ref name= "Skinner2009">Skinner, K., Cuiffetti, L. and Hyman, M., 2009. Metabolism and cometabolism of cyclic ethers by a filamentous fungus, a Graphium sp. Appl. Environ. Microbiol., 75(17), pp.5514-5522. [https://doi.org/10.1128/aem.00078-09 doi:10.1128/AEM.00078-09] [[media:Skinner2009.pdf| Article.pdf]]</ref>
+| ''Graphium'' sp. ATCC 58400 (fungus) || CYP || 4 ± 1 nmol/min/mg dry weight (with Propane) <br/>9 ± 5 nmol/min/mg dry weight (with THF) || Skinner et al. (2009)<ref name= "Skinner2009">Skinner, K., Cuiffetti, L. and Hyman, M., 2009. Metabolism and cometabolism of cyclic ethers by a filamentous fungus, a Graphium sp. Appl. Environ. Microbiol., 75(17), pp.5514-5522. [https://doi.org/10.1128/aem.00078-09 doi:10.1128/AEM.00078-09] [[media:Skinner2009.pdf| Article pdf]]</ref>
 |}
 [[1,4-Dioxane]] (14D) does not readily biodegrade in most anaerobic environments<ref name= "Shen2008">Shen, W., Chen, H. and Pan, S., 2008. Anaerobic biodegradation of 1, 4-dioxane by sludge enriched with iron-reducing microorganisms. Bioresource technology, 99(7), pp.2483-2487. [https://doi.org/10.1016/j.biortech.2007.04.054 doi: 10.1016/j.biortech.2007.04.054]</ref>. However, multiple studies have demonstrated that 14D can be biodegraded by a variety of microorganisms under aerobic conditions<ref name= "Mahendra2006">Mahendra, S. and Alvarez-Cohen, L., 2006. Kinetics of 1, 4-dioxane biodegradation by monooxygenase-expressing bacteria. Environmental Science & Technology, 40(17), pp.5435-5442. [https://doi.org/10.1021/es060714v doi:10.1021/es060714v]</ref><ref>Mahendra, S., Petzold, C.J., Baidoo, E.E., Keasling, J.D. and Alvarez-Cohen, L., 2007. Identification of the intermediates of in vivo oxidation of 1, 4-dioxane by monooxygenase-containing bacteria. Environmental Science & Technology, 41(21), pp.7330-7336. [https://doi.org/10.1021/es0705745 doi: 10.1021/es0705745]</ref><ref name="Skinner2009"/><ref name = "Sun2011">Sun, B., Ko, K. and Ramsay, J.A., 2011. Biodegradation of 1, 4-dioxane by a Flavobacterium. Biodegradation, 22(3), pp.651-659. [https://doi.org/10.1007/s10532-010-9438-9 doi: 10.1007/s10532-010-9438-9]</ref>. A summary of microorganisms that are reported to aerobically biodegrade 14D is presented in Table 1.
@@ Line 78: / Line 78: @@
 While several microorganisms have been isolated that can metabolize 14D<ref name= "Mahendra2006"/><ref name = "Kim2009"/><ref>Sei, K., Kakinoki, T., Inoue, D., Soda, S., Fujita, M. and Ike, M., 2010. Evaluation of the biodegradation potential of 1, 4-dioxane in river, soil and activated sludge samples. Biodegradation, 21(4), pp.585-591. [https://doi.org/10.1007/s10532-010-9326-3 doi: 10.1007/s10532-010-9326-3]</ref><ref name =  "Sei2013"/><ref name = "Huang2014"/>, these organisms are not common.  The best characterized 14D-metabolizing strain is ''Pseudonocardia dioxanivorans'' CB1190<ref name= "Mahendra2005"/>. This bacterium was originally enriched from industrial activated sludge, fed with [[wikipedia: Tetrahydrofuran | tetrahydrofuran]] (THF) and then subsequently fed with 14D<ref name= "Parales1994"/>.  The doubling time of CB1190 was about 30 hours when it was grown in ammonium mineral salts medium at 30 °C amended with 5.5 mM (484 mg/L) 14D<ref name= "Parales1994"/>.
-Degradation of 14D by strain CB1190 may be inhibited by elevated concentrations of [[Chlorinated Solvents | chlorinated solvents]] and their degradation products, and by some metals. Inhibition of 14D degradation was strongest for 1,1-dichloroethene (1,1-DCE) followed by ''cis''-1,2-diochloroethene (cDCE) > trichloroethene (TCE) > 1,1,1-trichloroethane (TCA). 14D biodegradation was completely inhibited by 5 mg/L 1,1-DCE<ref>Mahendra, S., Grostern, A. and Alvarez-Cohen, L., 2013. The impact of chlorinated solvent co-contaminants on the biodegradation kinetics of 1, 4-dioxane. Chemosphere, 91(1), pp.88-92. [https://doi.org/10.1016/j.chemosphere.2012.10.104 doi: 10.1016/j.chemosphere.2012.10.104]</ref><ref name= "Hand2015"/><ref name= "Zhang2016">Zhang, S., Gedalanga, P.B. and Mahendra, S., 2016. Biodegradation kinetics of 1, 4-dioxane in chlorinated solvent mixtures. Environmental Science & Technology, 50(17), pp.9599-9607. [https://doi.org/10.1021/acs.est.6b02797 doi: 10.1021/acs.est.6b02797] [[media:Zhang2016.pdf| Article.pdf]]</ref>. Cu(II) was the strongest metal inhibitor of 14D degradation by CB1190, causing an increase in the lag period at 1 mg/L and an order of magnitude reduction in 14D degradation rates at 10 and 20 mg/L Cu(II).  14D degradation was less sensitive to Cd(II) and Ni(II), while Zn(II) had no impact on 14D biodegradation at the maximum concentration tested (20 mg/L Zn)<ref>Pornwongthong, P., Mulchandani, A., Gedalanga, P.B. and Mahendra, S., 2014. Transition metals and organic ligands influence biodegradation of 1, 4-dioxane. Applied biochemistry and biotechnology, 173(1), pp.291-306. [https://doi.org/10.1007/s12010-014-0841-2 doi: 10.1007/s12010-014-0841-2]</ref>.
+Degradation of 14D by strain CB1190 may be inhibited by elevated concentrations of [[Chlorinated Solvents | chlorinated solvents]] and their degradation products, and by some metals. Inhibition of 14D degradation was strongest for 1,1-dichloroethene (1,1-DCE) followed by ''cis''-1,2-diochloroethene (cDCE) > trichloroethene (TCE) > 1,1,1-trichloroethane (TCA). 14D biodegradation was completely inhibited by 5 mg/L 1,1-DCE<ref>Mahendra, S., Grostern, A. and Alvarez-Cohen, L., 2013. The impact of chlorinated solvent co-contaminants on the biodegradation kinetics of 1, 4-dioxane. Chemosphere, 91(1), pp.88-92. [https://doi.org/10.1016/j.chemosphere.2012.10.104 doi: 10.1016/j.chemosphere.2012.10.104]</ref><ref name= "Hand2015"/><ref name= "Zhang2016">Zhang, S., Gedalanga, P.B. and Mahendra, S., 2016. Biodegradation kinetics of 1, 4-dioxane in chlorinated solvent mixtures. Environmental Science & Technology, 50(17), pp.9599-9607. [https://doi.org/10.1021/acs.est.6b02797 doi: 10.1021/acs.est.6b02797] [[media:Zhang2016.pdf| Article pdf]]</ref>. Cu(II) was the strongest metal inhibitor of 14D degradation by CB1190, causing an increase in the lag period at 1 mg/L and an order of magnitude reduction in 14D degradation rates at 10 and 20 mg/L Cu(II).  14D degradation was less sensitive to Cd(II) and Ni(II), while Zn(II) had no impact on 14D biodegradation at the maximum concentration tested (20 mg/L Zn)<ref>Pornwongthong, P., Mulchandani, A., Gedalanga, P.B. and Mahendra, S., 2014. Transition metals and organic ligands influence biodegradation of 1, 4-dioxane. Applied biochemistry and biotechnology, 173(1), pp.291-306. [https://doi.org/10.1007/s12010-014-0841-2 doi: 10.1007/s12010-014-0841-2]</ref>.
 [[File:Mahendra1w2 Fig1.png|thumb|left|Figure 1.  Growth Rates of Two 14D Metabolizers Versus 14D Concentration]]
@@ Line 94: / Line 94: @@
 ==Molecular Biological Tools==
-[https://enviro.wiki/index.php?title=Quantitative_Polymerase_Chain_Reaction_(qPCR) Quantitative polymerase chain reaction (qPCR)] quantifies the abundance of specific microorganisms and functional genes capable of degrading a particular contaminant.  qPCR analyses have been employed to quantify the abundance of microorganisms that can degrade 14D through the activity of tetrahydrofuran monooxygenase (THFMO) in samples from industrial activated sludge and groundwater<ref>Chiang, S.Y.D., Mora, R., Diguiseppi, W.H., Davis, G., Sublette, K., Gedalanga, P. and Mahendra, S., 2012. Characterizing the intrinsic bioremediation potential of 1, 4-dioxane and trichloroethene using innovative environmental diagnostic tools. Journal of Environmental Monitoring, 14(9), pp.2317-2326. [https://doi.org/10.1039/c2em30358b doi: 10.1039/C2EM30358B]</ref><ref>Gedalanga, P.B., Pornwongthong, P., Mora, R., Chiang, S.Y.D., Baldwin, B., Ogles, D. and Mahendra, S., 2014. Identification of biomarker genes to predict biodegradation of 1, 4-dioxane. Appl. Environ. Microbiol., 80(10), pp.3209-3218. [https://doi.org/10.1128/aem.04162-13 doi: 10.1128/AEM.04162-13] [[media:Gedalanga2014.pdf| Article.pdf]]</ref><ref>Li, M., Mathieu, J., Liu, Y., Van Orden, E.T., Yang, Y., Fiorenza, S. and Alvarez, P.J., 2013. The abundance of tetrahydrofuran/dioxane monooxygenase genes (thmA/dxmA) and 1, 4-dioxane degradation activity are significantly correlated at various impacted aquifers. Environmental Science & Technology Letters, 1(1), pp.122-127. [https://doi.org/10.1021/ez400176h doi: 10.1021/ez400176h]</ref><ref name= "Li2013"/><ref name= "Zhang2016"/>. However, care is warranted in the interpretation of qPCR results in other cases (e.g. propane-stimulated cometabolic 14D degradation) where the role of enzymes such as propane monooxygenase (PrMO) in 14D degradation is less clearly established.  Studies also suggest that these biomarkers can be used to detect the abundance of 14D-degraders ''in situ'' and quantify how they compete within the larger microbial community<ref>Miao, Y., Johnson, N.W., Gedalanga, P.B., Adamson, D., Newell, C. and Mahendra, S., 2019. Response and recovery of microbial communities subjected to oxidative and biological treatments of 1, 4-dioxane and co-contaminants. Water research, 149, pp.74-85. [https://doi.org/10.1016/j.watres.2018.10.070 doi:10.1016/j.watres.2018.10.070]</ref>. Microbial community analyses can be an asset towards guiding treatment strategies and predicting treatment synergies.
+[https://enviro.wiki/index.php?title=Quantitative_Polymerase_Chain_Reaction_(qPCR) Quantitative polymerase chain reaction (qPCR)] quantifies the abundance of specific microorganisms and functional genes capable of degrading a particular contaminant.  qPCR analyses have been employed to quantify the abundance of microorganisms that can degrade 14D through the activity of tetrahydrofuran monooxygenase (THFMO) in samples from industrial activated sludge and groundwater<ref>Chiang, S.Y.D., Mora, R., Diguiseppi, W.H., Davis, G., Sublette, K., Gedalanga, P. and Mahendra, S., 2012. Characterizing the intrinsic bioremediation potential of 1, 4-dioxane and trichloroethene using innovative environmental diagnostic tools. Journal of Environmental Monitoring, 14(9), pp.2317-2326. [https://doi.org/10.1039/c2em30358b doi: 10.1039/C2EM30358B]</ref><ref>Gedalanga, P.B., Pornwongthong, P., Mora, R., Chiang, S.Y.D., Baldwin, B., Ogles, D. and Mahendra, S., 2014. Identification of biomarker genes to predict biodegradation of 1, 4-dioxane. Appl. Environ. Microbiol., 80(10), pp.3209-3218. [https://doi.org/10.1128/aem.04162-13 doi: 10.1128/AEM.04162-13] [[media:Gedalanga2014.pdf| Article pdf]]</ref><ref>Li, M., Mathieu, J., Liu, Y., Van Orden, E.T., Yang, Y., Fiorenza, S. and Alvarez, P.J., 2013. The abundance of tetrahydrofuran/dioxane monooxygenase genes (thmA/dxmA) and 1, 4-dioxane degradation activity are significantly correlated at various impacted aquifers. Environmental Science & Technology Letters, 1(1), pp.122-127. [https://doi.org/10.1021/ez400176h doi: 10.1021/ez400176h]</ref><ref name= "Li2013"/><ref name= "Zhang2016"/>. However, care is warranted in the interpretation of qPCR results in other cases (e.g. propane-stimulated cometabolic 14D degradation) where the role of enzymes such as propane monooxygenase (PrMO) in 14D degradation is less clearly established.  Studies also suggest that these biomarkers can be used to detect the abundance of 14D-degraders ''in situ'' and quantify how they compete within the larger microbial community<ref>Miao, Y., Johnson, N.W., Gedalanga, P.B., Adamson, D., Newell, C. and Mahendra, S., 2019. Response and recovery of microbial communities subjected to oxidative and biological treatments of 1, 4-dioxane and co-contaminants. Water research, 149, pp.74-85. [https://doi.org/10.1016/j.watres.2018.10.070 doi:10.1016/j.watres.2018.10.070]</ref>. Microbial community analyses can be an asset towards guiding treatment strategies and predicting treatment synergies.
 [https://enviro.wiki/index.php?title=Compound_Specific_Isotope_Analysis_(CSIA) Compound specific isotope analysis (CSIA)] refers to measurement of the isotopic ratios of individual chemical compounds and can be used to differentiate contaminant sources, delineate reaction pathways, and provide evidence of ''in situ'' contaminant degradation.  CSIA methods are now available to measure isotopic fractionation of carbon and hydrogen<ref name= "Bennett2017"/>. For example, the aerobic biodegradation of 14D by a THF-grown 14D-degrading ''Pseudonocardia'' strain exhibited an isotopic fractionation factor (<big>''ε'' </big>) for carbon (<big>''ε''</big><sub>''c''</sub>)  of −4.73 ± 0.9‰ and hydrogen (<big>ε</big><sub>''H''</sub>) of -147  ± 22‰, respectively. Smaller <big>''ε''</big><sub>''c''</sub>and <big>ε</big><sub>''H''</sub> values, (-2.7 ± 0.3‰ and -21 ± 2‰, respectively) were determined for aerobic 14D degradation by a propane-grown ''Rhodococcus'' strain. As many ''Pseudonocardia'' strains use THFMO to initiate 14D degradation, CSIA, in conjunction with qPCR analyses, may be able to discriminate the roles of metabolism and cometabolism in 14D biodegradation at field sites<ref>Gedalanga, P., Madison, A., Miao, Y., Richards, T., Hatton, J., DiGuiseppi, W.H., Wilson, J. and Mahendra, S., 2016. A Multiple Lines of Evidence Framework to Evaluate Intrinsic Biodegradation of 1, 4‐Dioxane. Remediation Journal, 27(1), pp.93-114. [https://doi.org/10.1002/rem.21499 doi: 10.1002/rem.21499]</ref>.

@@ Line 6: / Line 6: @@
 *[[1,4-Dioxane]]
 *[[Biodegradation - Cometabolic]]
 '''Contributor(s):''' [[Dr. Shaily Mahendra]] and [[Dr. Michael Hyman]]
 '''Key Resource(s)''':

@@ Line 92: / Line 92: @@
 ==Molecular Biological Tools==
-[https://enviro.wiki/index.php?title=Quantitative_Polymerase_Chain_Reaction_(qPCR) Quantitative polymerase chain reaction (qPCR)] quantifies the abundance of specific microorganisms and functional genes capable of degrading a particular contaminant.  qPCR analyses have been employed to quantify the abundance of microorganisms that can degrade 14D through the activity of tetrahydrofuran monooxygenase (THFMO) in samples from industrial activated sludge and groundwater<ref>Chiang, S.Y.D., Mora, R., Diguiseppi, W.H., Davis, G., Sublette, K., Gedalanga, P. and Mahendra, S., 2012. Characterizing the intrinsic bioremediation potential of 1, 4-dioxane and trichloroethene using innovative environmental diagnostic tools. Journal of Environmental Monitoring, 14(9), pp.2317-2326. [https://doi.org/10.1039/c2em30358b doi: 10.1039/C2EM30358B]</ref><ref>Gedalanga, P.B., Pornwongthong, P., Mora, R., Chiang, S.Y.D., Baldwin, B., Ogles, D. and Mahendra, S., 2014. Identification of biomarker genes to predict biodegradation of 1, 4-dioxane. Appl. Environ. Microbiol., 80(10), pp.3209-3218. [https://doi.org/10.1128/aem.04162-13 doi: 10.1128/AEM.04162-13]</ref><ref>Li, M., Mathieu, J., Liu, Y., Van Orden, E.T., Yang, Y., Fiorenza, S. and Alvarez, P.J., 2013. The abundance of tetrahydrofuran/dioxane monooxygenase genes (thmA/dxmA) and 1, 4-dioxane degradation activity are significantly correlated at various impacted aquifers. Environmental Science & Technology Letters, 1(1), pp.122-127. [https://doi.org/10.1021/ez400176h doi: 10.1021/ez400176h]</ref><ref name= "Li2013"/><ref name= "Zhang2016"/>. However, care is warranted in the interpretation of qPCR results in other cases (e.g. propane-stimulated cometabolic 14D degradation) where the role of enzymes such as propane monooxygenase (PrMO) in 14D degradation is less clearly established.  Studies also suggest that these biomarkers can be used to detect the abundance of 14D-degraders ''in situ'' and quantify how they compete within the larger microbial community<ref>Miao, Y., Johnson, N.W., Gedalanga, P.B., Adamson, D., Newell, C. and Mahendra, S., 2019. Response and recovery of microbial communities subjected to oxidative and biological treatments of 1, 4-dioxane and co-contaminants. Water research, 149, pp.74-85. [https://doi.org/10.1016/j.watres.2018.10.070 doi:10.1016/j.watres.2018.10.070]</ref>. Microbial community analyses can be an asset towards guiding treatment strategies and predicting treatment synergies.
+[https://enviro.wiki/index.php?title=Quantitative_Polymerase_Chain_Reaction_(qPCR) Quantitative polymerase chain reaction (qPCR)] quantifies the abundance of specific microorganisms and functional genes capable of degrading a particular contaminant.  qPCR analyses have been employed to quantify the abundance of microorganisms that can degrade 14D through the activity of tetrahydrofuran monooxygenase (THFMO) in samples from industrial activated sludge and groundwater<ref>Chiang, S.Y.D., Mora, R., Diguiseppi, W.H., Davis, G., Sublette, K., Gedalanga, P. and Mahendra, S., 2012. Characterizing the intrinsic bioremediation potential of 1, 4-dioxane and trichloroethene using innovative environmental diagnostic tools. Journal of Environmental Monitoring, 14(9), pp.2317-2326. [https://doi.org/10.1039/c2em30358b doi: 10.1039/C2EM30358B]</ref><ref>Gedalanga, P.B., Pornwongthong, P., Mora, R., Chiang, S.Y.D., Baldwin, B., Ogles, D. and Mahendra, S., 2014. Identification of biomarker genes to predict biodegradation of 1, 4-dioxane. Appl. Environ. Microbiol., 80(10), pp.3209-3218. [https://doi.org/10.1128/aem.04162-13 doi: 10.1128/AEM.04162-13] [[media:Gedalanga2014.pdf| Article.pdf]]</ref><ref>Li, M., Mathieu, J., Liu, Y., Van Orden, E.T., Yang, Y., Fiorenza, S. and Alvarez, P.J., 2013. The abundance of tetrahydrofuran/dioxane monooxygenase genes (thmA/dxmA) and 1, 4-dioxane degradation activity are significantly correlated at various impacted aquifers. Environmental Science & Technology Letters, 1(1), pp.122-127. [https://doi.org/10.1021/ez400176h doi: 10.1021/ez400176h]</ref><ref name= "Li2013"/><ref name= "Zhang2016"/>. However, care is warranted in the interpretation of qPCR results in other cases (e.g. propane-stimulated cometabolic 14D degradation) where the role of enzymes such as propane monooxygenase (PrMO) in 14D degradation is less clearly established.  Studies also suggest that these biomarkers can be used to detect the abundance of 14D-degraders ''in situ'' and quantify how they compete within the larger microbial community<ref>Miao, Y., Johnson, N.W., Gedalanga, P.B., Adamson, D., Newell, C. and Mahendra, S., 2019. Response and recovery of microbial communities subjected to oxidative and biological treatments of 1, 4-dioxane and co-contaminants. Water research, 149, pp.74-85. [https://doi.org/10.1016/j.watres.2018.10.070 doi:10.1016/j.watres.2018.10.070]</ref>. Microbial community analyses can be an asset towards guiding treatment strategies and predicting treatment synergies.
 [https://enviro.wiki/index.php?title=Compound_Specific_Isotope_Analysis_(CSIA) Compound specific isotope analysis (CSIA)] refers to measurement of the isotopic ratios of individual chemical compounds and can be used to differentiate contaminant sources, delineate reaction pathways, and provide evidence of ''in situ'' contaminant degradation.  CSIA methods are now available to measure isotopic fractionation of carbon and hydrogen<ref name= "Bennett2017"/>. For example, the aerobic biodegradation of 14D by a THF-grown 14D-degrading ''Pseudonocardia'' strain exhibited an isotopic fractionation factor (<big>''ε'' </big>) for carbon (<big>''ε''</big><sub>''c''</sub>)  of −4.73 ± 0.9‰ and hydrogen (<big>ε</big><sub>''H''</sub>) of -147  ± 22‰, respectively. Smaller <big>''ε''</big><sub>''c''</sub>and <big>ε</big><sub>''H''</sub> values, (-2.7 ± 0.3‰ and -21 ± 2‰, respectively) were determined for aerobic 14D degradation by a propane-grown ''Rhodococcus'' strain. As many ''Pseudonocardia'' strains use THFMO to initiate 14D degradation, CSIA, in conjunction with qPCR analyses, may be able to discriminate the roles of metabolism and cometabolism in 14D biodegradation at field sites<ref>Gedalanga, P., Madison, A., Miao, Y., Richards, T., Hatton, J., DiGuiseppi, W.H., Wilson, J. and Mahendra, S., 2016. A Multiple Lines of Evidence Framework to Evaluate Intrinsic Biodegradation of 1, 4‐Dioxane. Remediation Journal, 27(1), pp.93-114. [https://doi.org/10.1002/rem.21499 doi: 10.1002/rem.21499]</ref>.

@@ Line 87: / Line 87: @@
 ==Anaerobic Biodegradation==
-To date, there is little evidence of metabolic or cometabolic anaerobic 14D biodegradation.  In a microcosm study using samples of aquifer material from several different 14D impacted sites, there was no evidence of 14D biodegradation<ref>Zenker, M.J., Borden, R.C. and Barlaz, M.A., 1999. Investigation of the intrinsic biodegradation of alkyl and cyclic ethers. The Fifth International In Situ and On-Site Bioremediation Symposium</ref>.  However, there is one study that reported anaerobic growth of an iron-reducing bacterium on 14D<ref name= "Shen2008"/>.
+To date, there is little evidence of metabolic or cometabolic anaerobic 14D biodegradation.  In a microcosm study using samples of aquifer material from several different 14D impacted sites, there was no evidence of 14D biodegradation<ref>Zenker, M.J., Borden, R.C. and Barlaz, M.A., 1999. Investigation of the intrinsic biodegradation of alkyl and cyclic ethers. The Fifth International In Situ and On-Site Bioremediation Symposium. Battelle Press. Cincinnati, OH</ref>.  However, there is one study that reported anaerobic growth of an iron-reducing bacterium on 14D<ref name= "Shen2008"/>.
 An indirect method of anaerobic 14D biodegradation exists via a microbially driven Fenton reaction. ''Shewanella oneidensis'', an Fe(III)-reducing facultative anaerobe, is able to generate hydroxyl radicals that can then break down 14D<ref>Sekar, R. and DiChristina, T.J., 2014. Microbially driven Fenton reaction for degradation of the widespread environmental contaminant 1, 4-dioxane. Environmental science & technology, 48(21), pp.12858-12867. [https://doi.org/10.1021/es503454a doi: 10.1021/es503454a]</ref>. Under anaerobic conditions, ''S. oneidensis'' produces Fe(II)  that can then interact chemically with H<sub>2</sub>O<sub>2</sub> to yield HO• radicals which can oxidatively degrade 1,4-dioxane.

@@ Line 10: / Line 10: @@
 '''Key Resource(s)''':
-*[https://doi.org/10.1016/j.jenvman.2017.05.033 Advances in bioremediation of 1,4-dioxane-contaminated waters]<ref>Zhang, S., Gedalanga, P.B. and Mahendra, S., 2017. Advances in bioremediation of 1, 4-dioxane-contaminated waters. Journal of environmental management, 204, pp.765-774. [https://doi.org/10.1016/j.jenvman.2017.05.033 doi: 10.1016/j.jenvman.2017.05.033] [[media:Zhang2016.pdf| Article.pdf]]</ref>
+*[https://doi.org/10.1016/j.jenvman.2017.05.033 Advances in bioremediation of 1,4-dioxane-contaminated waters]<ref>Zhang, S., Gedalanga, P.B. and Mahendra, S., 2017. Advances in bioremediation of 1, 4-dioxane-contaminated waters. Journal of environmental management, 204, pp.765-774. [https://doi.org/10.1016/j.jenvman.2017.05.033 doi: 10.1016/j.jenvman.2017.05.033]</ref>
 ==1,4-Dioxane Biodegradation==
@@ Line 76: / Line 76: @@
 While several microorganisms have been isolated that can metabolize 14D<ref name= "Mahendra2006"/><ref name = "Kim2009"/><ref>Sei, K., Kakinoki, T., Inoue, D., Soda, S., Fujita, M. and Ike, M., 2010. Evaluation of the biodegradation potential of 1, 4-dioxane in river, soil and activated sludge samples. Biodegradation, 21(4), pp.585-591. [https://doi.org/10.1007/s10532-010-9326-3 doi: 10.1007/s10532-010-9326-3]</ref><ref name =  "Sei2013"/><ref name = "Huang2014"/>, these organisms are not common.  The best characterized 14D-metabolizing strain is ''Pseudonocardia dioxanivorans'' CB1190<ref name= "Mahendra2005"/>. This bacterium was originally enriched from industrial activated sludge, fed with [[wikipedia: Tetrahydrofuran | tetrahydrofuran]] (THF) and then subsequently fed with 14D<ref name= "Parales1994"/>.  The doubling time of CB1190 was about 30 hours when it was grown in ammonium mineral salts medium at 30 °C amended with 5.5 mM (484 mg/L) 14D<ref name= "Parales1994"/>.
-Degradation of 14D by strain CB1190 may be inhibited by elevated concentrations of [[Chlorinated Solvents | chlorinated solvents]] and their degradation products, and by some metals. Inhibition of 14D degradation was strongest for 1,1-dichloroethene (1,1-DCE) followed by ''cis''-1,2-diochloroethene (cDCE) > trichloroethene (TCE) > 1,1,1-trichloroethane (TCA). 14D biodegradation was completely inhibited by 5 mg/L 1,1-DCE<ref>Mahendra, S., Grostern, A. and Alvarez-Cohen, L., 2013. The impact of chlorinated solvent co-contaminants on the biodegradation kinetics of 1, 4-dioxane. Chemosphere, 91(1), pp.88-92. [https://doi.org/10.1016/j.chemosphere.2012.10.104 doi: 10.1016/j.chemosphere.2012.10.104]</ref><ref name= "Hand2015"/><ref name= "Zhang2016">Zhang, S., Gedalanga, P.B. and Mahendra, S., 2016. Biodegradation kinetics of 1, 4-dioxane in chlorinated solvent mixtures. Environmental Science & Technology, 50(17), pp.9599-9607. [https://doi.org/10.1021/acs.est.6b02797 doi: 10.1021/acs.est.6b02797]</ref>. Cu(II) was the strongest metal inhibitor of 14D degradation by CB1190, causing an increase in the lag period at 1 mg/L and an order of magnitude reduction in 14D degradation rates at 10 and 20 mg/L Cu(II).  14D degradation was less sensitive to Cd(II) and Ni(II), while Zn(II) had no impact on 14D biodegradation at the maximum concentration tested (20 mg/L Zn)<ref>Pornwongthong, P., Mulchandani, A., Gedalanga, P.B. and Mahendra, S., 2014. Transition metals and organic ligands influence biodegradation of 1, 4-dioxane. Applied biochemistry and biotechnology, 173(1), pp.291-306. [https://doi.org/10.1007/s12010-014-0841-2 doi: 10.1007/s12010-014-0841-2]</ref>.
+Degradation of 14D by strain CB1190 may be inhibited by elevated concentrations of [[Chlorinated Solvents | chlorinated solvents]] and their degradation products, and by some metals. Inhibition of 14D degradation was strongest for 1,1-dichloroethene (1,1-DCE) followed by ''cis''-1,2-diochloroethene (cDCE) > trichloroethene (TCE) > 1,1,1-trichloroethane (TCA). 14D biodegradation was completely inhibited by 5 mg/L 1,1-DCE<ref>Mahendra, S., Grostern, A. and Alvarez-Cohen, L., 2013. The impact of chlorinated solvent co-contaminants on the biodegradation kinetics of 1, 4-dioxane. Chemosphere, 91(1), pp.88-92. [https://doi.org/10.1016/j.chemosphere.2012.10.104 doi: 10.1016/j.chemosphere.2012.10.104]</ref><ref name= "Hand2015"/><ref name= "Zhang2016">Zhang, S., Gedalanga, P.B. and Mahendra, S., 2016. Biodegradation kinetics of 1, 4-dioxane in chlorinated solvent mixtures. Environmental Science & Technology, 50(17), pp.9599-9607. [https://doi.org/10.1021/acs.est.6b02797 doi: 10.1021/acs.est.6b02797] [[media:Zhang2016.pdf| Article.pdf]]</ref>. Cu(II) was the strongest metal inhibitor of 14D degradation by CB1190, causing an increase in the lag period at 1 mg/L and an order of magnitude reduction in 14D degradation rates at 10 and 20 mg/L Cu(II).  14D degradation was less sensitive to Cd(II) and Ni(II), while Zn(II) had no impact on 14D biodegradation at the maximum concentration tested (20 mg/L Zn)<ref>Pornwongthong, P., Mulchandani, A., Gedalanga, P.B. and Mahendra, S., 2014. Transition metals and organic ligands influence biodegradation of 1, 4-dioxane. Applied biochemistry and biotechnology, 173(1), pp.291-306. [https://doi.org/10.1007/s12010-014-0841-2 doi: 10.1007/s12010-014-0841-2]</ref>.
 [[File:Mahendra1w2 Fig1.png|thumb|left|Figure 1.  Growth Rates of Two 14D Metabolizers Versus 14D Concentration]]