Biodegradation of N-hexadecane using bacterial consortium isolated from seawater contaminated with petroleum

This study is aimed at determining the biodegradation potential of n-hexadecane by three bacterial strains (Pseudomonas aeruginosa, Bacillus subtilis, and Bacillus Paralicheniformis) isolated from seawater contaminated with petroleum. The effects of parameters, including the surfactant (Tween 20, Tween 80, and sodium dodecyl sulfate (SDS)), concentration (1-4 CMC (critical micelle concentration)), n-hexadecane concentration (0.5-5%), and bacterial consortium volume (5-20 mL), were investigated on the biodegradation of n-hexadecane. Finally, intermediate compounds resulting from the biodegradation of n-hexadecane were determined. Based on the results, the highest biodegradation of n-hexadecane (80.34%) was obtained in Tween 80 surfactant after 21 days compared to SDS (46.17%) and Tween 20 (72.97%) surfactants. The lowest and highest biodegradation of n-hexadecane (%) at the end of day 21 was obtained at concentrations of 1 (80.14%) and 4 (90.82%) CMC of Tween 80 surfactant, respectively. The biodegradation of n-hexadecane (%) significantly increased (98.8%) at the end of 21 days when the bacterial consortium was utilized in high volume (20 mL). The highest biodegradation of n-hexadecane (%) occurred at a concentration of 0.5% and reached 99.12% after 70 days. In addition, the Pseudomonas aeruginosa strain biodegraded n-hexadecane better after 21 days (25.15%) compared to Bacillus subtilis (20.5%) and Bacillus Paralicheniformis (16.8%). Biodegradation of n-hexadecane by these bacteria produced n-tridecane-1-ol, 2-hexadecanol, n-hexadecanoic acid, and 1-hexadecanol as intermediates. The results indicated that the synergy of bacterial consortium and surfactant could improve the biodegradation of n-hexadecane.