Optimization of Phenanthrene-degradation by Dietzia Cinnamea AP for Bioremediation Applications

Background: This study focused on isolation and identification of a Phenanthrene (Phe) degrader bacterium and optimization of environmental conditions for Phe degradation. Materials and Methods: Enrichment technique was used for isolation and the most effective isolate; named AP was selected based on its Phe biodegradation abilities. The isolate was identified using morphological and biochemical tests as well as۱۶S rDNA sequencing. The effects of various factors such as temperature, pH and C/N on bacterial growth and Phe degradation were investigated using protein assay (Bradford) and Gas Chromatography (GC), respectively. Results: The selected isolate was identified as Dietzia cinnamea AP. It was able to degrade Phe at pH ۶-۱۰ (optimum at ۸), temperatures of ۲۵ -۴۵ °C (optimum at ۳۵ °C) and NH۴Cl concentrations of ۰.۵-۲.۵ gL-۱ (optimum at ۲ g L-۱). By optimization of environmental parameters, within ۱۰ days of fermentation, Phe degradation rate increased by more than ۱.۲ fold (from ۶۰% to ۷۳%). Conclusion: D. cinnamea AP was found to be an appropriate candidate for bioremediation applications. To the best of our knowledge, this is the first report of D. cinnamea species that can degrade Phe.