Characteristics of Anaerobic Benzo(a)pyrene Biodegradation by C. cellulans CWS2

Anaerobic polycyclic aromatic hydrocarbons (PAHs) biodegradation is highly important for treating PAHs-contaminated aquifers without oxygen. The aim of this study was to investigate the biodegradation characteristics of benzo(a) pyrene (BaP) in aqueous solution by C. cellulans CWS2 under anaerobic conditions. The degradation characteristics include different temperatures (20–35°C), different pH values (7.0–12.0), and different BaP concentrations (0, 2.5, 5.0, 10.0, 25.0, 50.0 mg/L). The behavior after adding other PAHs and an additional carbon source was also evaluated. C. cellulans CWS2 could degrade BaP at a concentration of 25.0 mg/L in the temperature range of 20–35°C, and approximately 58% of the biodegradation was achieved at 35°C within 10 days at a natural pH. The alkaline conditions of 7.0–10.0 favor biodegradation and reached their highest point at pH 10.0. A BaP concentration of 10.0 mg/L with an initial value of 1.85 at OD600 nm for degradation of the BaP system and a pH of 7.0 was the most ideal condition for obtaining the highest degradation ratio, which was above 80% or higher. C. cellulans CWS2 could degrade phenanthrene and pyrene at the same time, and a low concentration of phenanthrene and pyrene did not reduce BaP degradation. BaP metabolism by C. cellulans CWS2 under anaerobic conditions was the sole carbon and energy source even when there was an additional available carbon source.