Aerobic Biotransformation of Gasoline Aromatics in MultiComponent Mixtures

Authors: Deeb, Rula A.; Alvarez-Cohen, Lisa

Source: Bioremediation Journal, Volume 4, Number 2, April-June 2000 , pp. 171-179(9)

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Abstract:

The primary objective of this study was to evaluate the impact of substrate interactions on the biotransformation rates and mineralization potentials of gasoline monoaromatics and methyl tert -butyl ether (MTBE), compounds that commonly co-exist in groundwater contaminant plumes. A mixed culture was derived from gasoline-contaminated aquifer material using toluene as the enrichment substrate. Two pure cultures, Rhodococcus sp. RR1 and RR2, were isolated from the mixed culture. The three toluene-grown cultures were shown to biotransform all of the six BTEX compounds (benzene, toluene, ethylbenzene, o -xylene, m -xylene, and p -xylene), both individually and in mixtures, over a broad range of concentrations. The mixed culture was shown to degrade all of the BTEX compounds to 14 CO 2 , while the two isolates mineralized BTE( m -/ p -)X, but biotransformed o -xylene without production of carbon dioxide. Studies to evaluate substrate interactions caused by the concurrent presence of multiple BTEX compounds during their biodegradation revealed a number of patterns ,including competitive inhibition and cometabolism. Ethylbenzene was shown to significantly inhibit BTX degradation in mixtures. MTBE was not biodegraded by any of the three toluene-grown cultures over a range of MTBE concentrations. Furthermore, the presence of MTBE at concentrations of 2 to 100 mg/L had no effect on BTEX biotransformation rates.

Document Type: Research article

DOI: http://dx.doi.org/10.1080/10889860091114211

Affiliations: 1: Department of Civil and Environmental Engineering; 631 Davis Hall, MC 1710 University of California at Berkeley, Berkeley, California 94720-1710

Publication date: 2000-04-01