Biological Degradation of Heterocyclic Aromatic Hydrocarbons with Naphthalene-Enriched Consortium: Substrate Interaction Studies and Fate of Metabolites

The current work has attempted to understand the substrate interaction between aromatic compounds of similar and divergent nature and the significance of their interactions on the biodegradation kinetics of compounds in a mixture. The chosen representative compounds for the present study are pyridine, quinoline, benzothiophene, benzofuran and naphthalene. Biodegradation studies were performed on binary, ternary, and multipollutant systems. Benzothiophene and benzofuran were the most persistent contaminants and they exhibit a significant inhibitory effect on the biodegradation of other co-contaminants, especially pyridine. The effects of different NSO compounds on naphthalene biodegradation and vice versa were also investigated. The presence of naphthalene (50 mg/L) enhanced the rate of biodegradation of both benzothiophene (50 mg/L) and benzofuran (50 mg/L) by 40.4 and 23.91 %, respectively. Distinct variation in composition and biodegradability of transition metabolites were observed during multisubstrate degradation. The presence of benzothiophene and benzofuran also significantly inhibited the degradation of prominent metabolic intermediates resulting in their accumulation in the system for a very longer period of time. An attempt was also made to simulate the biodegradation kinetics in a multipollutant system using a mathematical model. The multisubstrate model predicted the behavior of these systems satisfactorily.