Biodegradation of thiophene, benzothiophene, and benzofuran with eight different primary substrates

The aerobic biodegradation of thiophene, benzothiophene, and benzofuran was studied in microcosm experiments using groundwater microorganisms as inoculum. Benzofuran, a heterocyclic aromatic compound containing oxygen, was biodegraded as a sole source of carbon and energy measured by the disappearance of the compound, whereas two heterocyclic aromatic compounds containing sulphur (thiophene and benzothiophene) were not used as growth substrates. Thiophene was biodegraded with benzene, toluene, and to some extent ethylbenzene as primary substrates. Some biodegradation of thiophene was observed when p-xylene, o-xylene, m-xylene, naphthalene, and 1- methylnaphthalene were the primary substrates. Benzothiophene was completely trans formed, with all eight primary substrates investigated except for benzene and p-xylene, in which 34 and 6% of benzothiophene, respectively, remained after 40 d of incubation. Although benzofuran could be used as a sole source of carbon and energy, data showed that the biodegradation of benzofuran definitely was enhanced by the biodegradation of the primary substrates used.