Substrate Interactions during the Biodegradation of Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) Hydrocarbons by the Fungus Cladophialophora sp. Strain T1

ABSTRACT The soil fungus Cladophialophora sp. strain T1 (= ATCC MYA-2335) was capable of growth on a model water-soluble fraction of gasoline that contained all six BTEX components (benzene, toluene, ethylbenzene, and the xylene isomers). Benzene was not metabolized, but the alkylated benzenes (toluene, ethylbenzene, and xylenes) were degraded by a combination of assimilation and cometabolism. Toluene and ethylbenzene were used as sources of carbon and energy, whereas the xylenes were cometabolized to different extents. o-Xylene and m-xylene were converted to phthalates as end metabolites; p-xylene was not degraded in complex BTEX mixtures but, in combination with toluene, appeared to be mineralized. The metabolic profiles and the inhibitory nature of the substrate interactions indicated that toluene, ethylbenzene, and xylene were degraded at the side chain by the same monooxygenase enzyme. Our findings suggest that soil fungi could contribute significantly to bioremediation of BTEX pollution.

Sensory and Chemical Characterization of Fish Tainted by Exposure to Oil Sand Wastewaters

To investigate the potential for fish tainting from exposure to oil sands extraction wastewaters, rainbow trout were exposed to four different tailings pond wastewaters for a period of 24 hours. Subsequently, the fish were sacrificed, filleted and bile drawn from the gall bladder. Sensory analysis, performed by 10 pre-screened panelists, revealed that each of the four wastewater streams tainted the exposed fish to a detectable degree. Chemical analyses of the fish fillet, wastewater and fish bile revealed the presence of alkylated benzenes and phenols. The total level of phenols detected in the fish tissue was well above reported odour threshold levels. The additional presence of organic sulphur compounds identified in the wastewater suggests that they may also have contributed to the detected level of fish taint.