Isolation and characterization of two aerobic bacterial strains that completely degrade ethyl tert -butyl ether (ETBE)

Abstract

Two bacterial strains, E1 and E2, isolated from gasoline-polluted soil completely degraded ethyl tert-butyl ether (ETBE), as the sole source of carbon and energy, at specific rates of about 80 mg g(-1) and 58 mg g(-1) of cell protein day(-1), respectively. On the basis of morphological and phenotypic characteristics, strain E1 was tentatively identified as Comamonas testosteroni and strain E2 as belonging to Centre for Disease Control group A-5. The inhibitory effect of metyrapone on the degradative ability of both strains was the first evidence indicating the involvement of a soluble cytochrome P-450 in the cleavage of the ETBE ether bond. This observation was confirmed by spectrophotometric analysis of reduced cell extracts that gave, in the presence of carbon monoxide, a major absorbance peak at about 450 nm. Both strains were also able to degrade, as the sole source of carbon and energy, ETBE's major metabolic intermediates (tert-butyl alcohol and tert-butyl formate) and other gasoline oxygenates (methyl tert-butyl ether and tert-amyl methyl ether). The degradation rates varied considerably, with both strains exhibiting a preferential activity for ETBE's metabolic intermediates.

Genes Involved in the Degradation of Ether Fuels by Bacteria of the Mycobacterium/Rhodococcus Group

“…This hypothesis is further supported by the observation that the well-known camphoroxidizing cytochrome P-450 cam is able to degrade MTBE partially [2]. In addition, even if indirect evidence suggests that cytochrome P-450 systems participate in the degradation of ether fuels by several microorganisms [2,10,19], this may not be always the case: the cleavage of MTBE by Mycobacterium austroafricanum IFP 2012 appears to involve a nonheme monooxygenase [7]. Owing to this diversity, it is likely that more genes from different ether fuel-degrading microorganisms will have to be cloned in order to get a fully representative panel of probes for monitoring the MTBE-and ETBE-degrading potential of the microflora.…”

“…TBA can then be further metabolized, either by the same microorganism [2,[5][6][7] or by other microorganisms living in the same natural or artificial consortium [9][10][11]. Therefore, strategies can be developed for the bioremediation of pollution by ether fuels, based on the addition of selected strains (bioaugmentation), on the optimization of growth conditions (biostimulation), or both.…”

Cloning of a Genetically Unstable Cytochrome P-450 Gene Cluster Involved in Degradation of the Pollutant Ethyl tert -Butyl Ether by Rhodococcus ruber

“…Oxidation of both MTBE and TBA involves a soluble cytochrome P-450, which most likely corresponds to the propane monooxygenase. Comamonas testoteroni E1 and the gram-positive bacterial strain E2 have been recently isolated as ether fuel degraders (21). Metyrapone inhibition and spectrophotometric analysis strongly suggested that degradation of ETBE by both strains involves a cytochrome P-450.…”

Identification of tertiary butyl alcohol (TBA)-utilizing organisms in BioGAC reactors using 13C-DNA stable isotope probing

“…Although TBA is often only slowly biodegraded under anaerobic conditions (Wilson et al 2005), rapid aerobic TBA biodegradation has been demonstrated in microcosm studies using stream bed sediments (Bradley et al 1999), surface water sediments (Bradley et al 2002) and various cultures (Deeb et al 2003;Fortin et al 2001;François et al 2002;Hanson et al 1999;Hatzinger et al 2001;Kharoune et al 2001;Mo et al 1997;Piveteau et al 2001;Salanitro et al 1994;Steffan et al 2000). Several pure cultures of aerobic TBA-utilizing bacteria have also been isolated and characterized.…”