Enhancement of phenol degradation by free and immobilized mixed culture of Providencia stuartii PL4 and Pseudomonas aeruginosa PDM isolated from activated sludge

Abstract

Biodegradation of phenol has been investigated using a bacterial consortium consisting of two bacterial isolates; one of them used for the first time in phenol biodegradation. This consortium was isolated from activated sludge and identified as Providencia stuartii PL4 and Pseudomonas aeruginosa PDM (accession numbers KY848366 and MF445102, respectively). The degradation of phenol by this consortium was optimal at pH 7 with using 1500 mg l⁻¹ ammonium chloride as a nitrogen source. Interestingly, after optimizing the biodegradation conditions, this consortium was able to degrade phenol completely up to 1500 mg l⁻¹ within 58 h. The immobilization of this consortium on various supporting materials indicated that polyvinyl alcohol (PVA)-alginate beads and polyurethane foam (PUF) were more suitable for biodegradation process. The freely suspended cells could degrade only 6% (150 mg l⁻¹) of 2500 mg l⁻¹ phenol, whereas, the immobilized PVA-alginate beads and the immobilized PUF degraded this concentration completely within 120 h of incubation with degradation rates (q) 0.4839 and 0.5368 (1/h) respectively. Thus, the immobilized consortium of P. stuartii PL4 and P. aeruginosa PDM can be considered very promising in the treatment of effluents containing phenol.

Keywords:

• Degradation rate
• freely suspended cells
• phenol
• polyurethane foam
• polyvinyl alcohol – alginate
• Providencia stuartii

Disclosure statement

The authors declare that they have no conflict of interest.

Additional information

Funding

The authors are thankful to National Research Center, Giza, Egypt for the funding of this work [grant number 8/1/13].