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

Abstract

Abstract-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 transformed, 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.

Concomitant aerobic biodegradation of benzene and thiophene

“…Cometabolic reactions among aromatic compounds under aerobic conditions have been observed before. In previous studies [12,20], we observed that the condensed thiophenes likely were degraded cometabolically. But cometabolic reactions also have been observed among the monoaromatic compounds.…”

“…In other experiments, using groundwater microorganisms from another creosote‐contaminated site and other groundwater microorganisms originating from the same aquifer as used in this study, it was observed that benzene may be used as growth substrate in the removal of thiophene [8,12,20]. It was also stated that the biodegradation of thiophene seemed to occur concomitantly with the biodegradation of benzene [12,20], but no strong conclusions were made at that time because of limitations in the data.…”

“…This may explain why benzene is detected in the groundwater at creosote‐contaminated sites where a complex mixture of organic compounds are present. Other experiments have indicated that thiophene only can be biodegraded by cometabolic processes where concomitant biodegradation of other compounds is occurring [8–12].…”

Biodegradation of Various Aromatic Compounds by Enriched Bacterial Cultures: Part B—Nitrogen-, Sulfur-, and Oxygen-Containing Heterocyclic Aromatic Compounds

“…S2c). Dyreborg et al [21] showed that although benzofuran could be used as a sole source of carbon and energy, its degradation could be enhanced in presence of a primary substrate. Degradation of benzofuran occurs by lateral dioxygenation which is catalyzed mainly by naphthalene dioxygenases.…”

“…Studies on biodegradation of oxygen-containing heterocyclic compound benzofuran are very limited. Dyreborg et al [21] reported effective degradation of benzofuran as a single substrate as well as in the presence of other primary substrates such as naphthalene and 1-methylnaphthalene. However, there is no report on mechanism and identification of metabolites formed during benzofuran biodegradation.…”