Nitrogen Biogeochemistry of Anaerobic Biodegradation of Naphthalene

A mixed community of bacteria was enriched from groundwater contaminated with naphthalene as the sole carbon source. Based on the results of 16S rRNA sequences, Acinetobacter and Pseudomonas were the predominant species in the naphthalene-enriched culture. Different initial forms of nitrogen, including nitrate, nitrite, and ammonium, were beneficial to naphthalene degradation, which was considered second-order kinetics and naphthalene could be decreased by 94.68% during the incubation period of 30 days with an initial naphthalene concentration of 0.5 mg/L. These clear biogeochemical denitrification signals, the consumption and accumulation of nitrate, nitrite, and ammonium during the incubation period, suggested that naphthalene degradation may be coupled with denitrification and DNRA metabolism. Nitrate and nitrite were reduced mainly as electron acceptors, and ammonium was utilized by microorganisms as an important inorganic nutrient for their growth and reproduction, which promoted the degradation of naphthalene. The results of this study contributed to the removal pathway and transformational mechanism of nitrogen and reveal their involvement in the anaerobic biodegradation of naphthalene.