Biodegradation of fluoranthene by Paenibacillus sp. strain PRNK-6: a pathway for complete mineralization

A high-efficiency fluoranthene-degrading bacterium Paenibacillus sp. PRNK-6 was isolated from PAH-contaminated soil. The strain degrades 96% (240 mg l^-1) of fluoranthene in 48 h. Various metabolic intermediates of fluoranthene catabolism were identified by gas chromatography (GC) and gas chromatography-high resolution mass spectrometry (GC-HRMS). Metabolite characterization, metabolite-feeding experiments, and appropriate enzyme activities in the cell-free extracts suggest the existence of a bifurcated pathway down the phthalic acid for complete mineralization of fluoranthene in PRNK-6. In this strain, fluoranthene catabolism begins by the attack on the fused aromatic ring portion of fluoranthene. Two terminal aromatic metabolites protocatechuate and catechol undergo ring cleavage by protocatechuate 3,4-dioxygenase and catechol 1,2-dioxygenase, respectively, and enter the central metabolism.