Fluorene, phenanthrene, and pyrene degradation by a bacterial consortium enriched from rice field sediments

Polycyclic aromatic hydrocarbons (PAHs) pose a significant environmental challenge due to their toxicity that are harmful to living organisms, and commonly found in various ecosystems. Degradation using natural indigenous bacteria is the most cost-effective solution to remove PAHs in the environment. This study examines Sdt-1, an isolated bacterial consortium from agricultural soil in Wakabayashi-ward, Sendai, Japan, capable of degrading PAHs. Sdt-1 was incubated to a solution containing fluorene, phenanthrene, and pyrene in Bushnell Hass Medium (BHM) with 100 mg/L concentration of each compound. Fluorene degraded at the fastest rate, then phenanthrene, while pyrene was the slowest due to its higher molecular weight. Cloning of the 16S rRNA gene showed that Sdt-1 consists primarily of 48% Castellaniella, 16% Mycobacterium, 14% Desulfonatronum, 10% Azospirillum, and 2% each of several other genera. The dynamics of the Sdt-1 was tracked over the 15-d incubation periods through the PCR-DGGE analysis, showing Mycobacterium as the dominant PAH degrader. Correlation between bacterial activity and PAH-degrading genes (nidA and gram-positive PAH-RDH) demonstrates that specific microbes are in charge of various degradation phases. This study enhanced our understanding of the mechanics, characteristics, and the potential role for bioremediation applications of aerobic PAH-degrading bacteria from paddy soil in agricultural land.