Biotreatability Kinetics

Grady, C. P. Leslie; Sock, Shawn M.; Cowan, Robert M.

doi:10.1007/978-1-4615-5395-3_28

Cited by 3 publications

(1 citation statement)

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“…However, these processes are expensive and require ex situ treatment of groundwater. Biodegradation of dioxane has been reported for several pure and mixed cultures of bacteria ( − ) and fungi ( , ). While some isolates cometabolically degraded dioxane after using compounds such as propane () or tetrahydrofuran ( , ) as primary growth substrates, other isolates were able to utilize dioxane as the sole carbon and energy source ( 9 , 11 , 12 , 17 ).…”

Section: Introductionmentioning

confidence: 99%

Identification of the Intermediates of in Vivo Oxidation of 1,4-Dioxane by Monooxygenase-Containing Bacteria

Mahendra

Kim

Baidoo

et al. 2007

Environ. Sci. Technol.

114

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1,4-dioxane is a probable human carcinogen and an emerging water contaminant. Monooxygenase-expressing bacteria have been shown to degrade dioxane via growth-supporting as well as cometabolic mechanisms. In this study, the intermediates of dioxane degradation by monooxygenase-expressing bacteria were determined by triple quadrupole-mass spectrometry and Fourier transform ion cyclotron resonance-mass spectrometry. The major intermediates were identified as 2-hydroxyethoxyacetic acid (HEAA), ethylene glycol, glycolate, and oxalate. Studies with uniformly labeled 14C dioxane showed that over 50% of the dioxane was mineralized to CO2 by CB1190, while 5% became biomass-associated after 48 h. Volatile organic acids and non-volatiles, respectively, accounted for 20 and 11% of the radiolabeled carbon. Although strains cometabolizing dioxane exhibited limited transformation capacities, nearly half of the initial dioxane was recovered as CO2. On the basis of these analytical results, we propose a pathway for dioxane oxidation by monooxygenase-expressing cells in which dioxane is first converted to 2-hydroxy-1,4-dioxane, which is spontaneously oxidized to HEAA. During a second monooxygenation step, HEAA is further hydroxylated, resulting in a mixture of dihydroxyethoxyacetic acids with a hydroxyl group at the ortho or para position. After cleavage of the second ether bond, small organic molecules such as ethylene glycol, glycolate, glyoxalate, and oxalate are progressively formed, which are then mineralized to CO2 via common cellular metabolic pathways. Bioremediation of dioxane via this pathway is not expected to cause an accumulation of toxic compounds in the environment.

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