Biodegradation of Ether Pollutants by Pseudonocardia sp. Strain ENV478

Abstract

A bacterium designated Pseudonocardia sp. strain ENV478 was isolated by enrichment culturing on tetrahydrofuran (THF) and was screened to determine its ability to degrade a range of ether pollutants. After growth on THF, strain ENV478 degraded THF (63 mg/h/g total suspended solids [TSS]), 1,4-dioxane (21 mg/h/g TSS), 1,3-dioxolane (19 mg/h/g TSS), bis-2-chloroethylether (BCEE) (12 mg/h/g TSS), and methyl tert-butyl ether (MTBE) (9.1 mg/h/g TSS). Although the highest rates of 1,4-dioxane degradation occurred after growth on THF, strain ENV478 also degraded 1,4-dioxane after growth on sucrose, lactate, yeast extract, 2-propanol, and propane, indicating that there was some level of constitutive degradative activity. The BCEE degradation rates were about threefold higher after growth on propane (32 mg/h/g TSS) than after growth on THF, and MTBE degradation resulted in accumulation of tert-butyl alcohol. Degradation of 1,4-dioxane resulted in accumulation of 2-hydroxyethoxyacetic acid (2HEAA). Despite its inability to grow on 1,4-dioxane, strain ENV478 degraded this compound for >80 days in aquifer microcosms. Our results suggest that the inability of strain ENV478 and possibly other THF-degrading bacteria to grow on 1,4-dioxane is related to their inability to efficiently metabolize the 1,4-dioxane degradation product 2HEAA but that strain ENV478 may nonetheless be useful as a biocatalyst for remediating 1,4-dioxane-contaminated aquifers.

Metabolism and Cometabolism of Cyclic Ethers by a Filamentous Fungus, aGraphiumsp

“…8) (28). The lack of sustained 14D oxidation in THFgrown Pseudonocardia ENV478 has been suggested to be due in part to the generation of intermediates such as 2-hydroxyethoxyacetic acid (45). This acid is thought to be generated from 2-hydroxyethoxy-2-acetaldehyde, which is the tautomer of the immediate hydroxylated product of 14D oxidation, 1,4-dioxane-2-ol (45).…”

“…Because this chlorinated hydrocarbon is one of the most frequently encountered groundwater pollutants in the United States, there is concern over the environmental fate of cyclic ethers that are likely cocontaminants at sites contaminated with 1,1,1-trichloroethane (27,40,44). Currently, 14D is not known to be used widely as a growth substrate by microorganisms, but a number of studies have demonstrated that 14D can be oxidized cometabolically by aerobic organisms that grow on THF or other substrates, such as toluene or n-alkanes (4,28,45,49). Notably, this group of organisms includes Mycobacterium vaccae JOB5 (4) and Pseudonocardia sp.…”

“…strain ENV478. These strains also oxidize another important ether pollutant, methyl tert-butyl ether (MTBE) (41,45).…”

“…Many actinomycetes have been identified that can utilize THF as a sole source of carbon and energy under aerobic conditions. Among these organisms are multiple Rhodococcus isolates, including Rhodococcus ruber strains 219 (2,3) and M2 (12), a number of closely related Pseudonocardia strains, including Pseudonocardia dioxanivorans (25,35), Pseudonocardia benzenivorans (17), Pseudonocardia sulfidooxydans (17,27), Pseudonocardia hydrocarbonoxydans (17), and Pseudonocardia tetrahydrofuranoxydans strains K1 (21), M1 (12), and ENV478 (45), and the Nocardia-like propanotroph strain ENV 425 (45). Fungal growth on THF by Aureobasidium pullulans has been reported for a patent (36), and growth of Cordyceps sinensis on THF, tetrahydropyran, and other cyclic ethers, including 1,3-dioxane (13D), 1,4-dioxane (14D), and several methyl dioxanes, was also recently described (33).…”

Éter típusú üzemanyag-adalékok mikrobiális bontása

“…ENV478 tetrahidrofuránon nőtt tenyészete az MTBE-t TBA-vá oxidálta [103]. A reakciót valószínűleg a törzs tetrahidrofurán monooxigenáz enzime katalizálta, mely az alkán hidroxilázok rokonsági körébe tartozik.…”