Synergic degradation of phenanthrene by consortia of newly isolated bacterial strains.

Three different bacteria capable of degrading phenanthrene were isolated from sludge of a pulp wastewater treatment plant and identified as Acinetobacter baumannii, Klebsiella oxytoca, and Stenotrophomonas maltophilia. Phenanthrene degradation efficiencies by different combinations (consortia) of these bacteria were investigated and their population dynamics during phenanthrene degradation were monitored using capillary electrophoresis-based single-strand conformation polymorphism (CE-SSCP). When a single microorganism was used, phenanthrene degradation efficiency was very low (48.0, 11.0, and 9.0% for A. baumannii, K. oxytoca, and S. maltophilia respectively, after 360 h cultivation). All consortia that included S. maltophilia degraded approximately 80.0% of phenanthrene and reduced lag time to 48 h compared to the 168 h of pure A. baumannii culture. CE-SSCP analysis showed that S. maltophilia was the predominant species during phenanthrene degradation in the mixed culture. The results indicate that mixed cultures of microorganisms may effectively degrade target chemicals, even if the microorganisms show low degradation activity in pure culture.