Synergistic biodegradation of phenanthrene and fluoranthene by mixed bacterial cultures

Polycyclic aromatic hydrocarbons (PAHs) are highly recalcitrant compounds and difficult to degrade. Therefore in this work, using a bioremediation approach, mixed bacterial cultures (ASPF) was developed and enriched from polluted marine sediments capable of degrading 400 mg/L of phenanthrene and fluoranthene in Bushnell Hass medium. ASPF consists of 22 bacterial genera dominated by Azoarcus and Chelativorans. The biostimulation effect of three water soluble fertilizers (NPK, urea, and ammonium sulfate) showed that NPK and ammonium sulfate have enhanced the degradation, whereas urea has decreased their degradation. ASPF was also able to degrade phenanthrene and fluoranthene in the presence of petroleum hydrocarbons. But degradation was found to decrease in the presence of pathway intermediates (phthalic acid and catechol) due to enzymatic feedback inhibition. Optimum degradation of both PAHs was observed under room temperature, suggesting the practical applicability of ASPF.