Study of the degradation activity and the strategies to promote the bioavailability of phenanthrene by Sphingomonas paucimobilis strain 20006FA

COPPOTELLI B.M., IBARROLAZA A., DIAS R.L., DEL PANNO M.T., BERTHE-CORTI L. AND MORELLI I. S

MICROBIAL ECOLOGY

Springer Science

Lugar: New York; Año: 2009

0095-3628

The present study describes the phenanthrenedegradingactivity of Sphingomonas paucimobilis 20006FAand its ability to promote the bioavailability of phenanthrene.S. paucimobilis 20006FA was isolated from a phenanthrenecontaminatedsoil microcosm. The strain was able to grow inliquid mineral medium saturated with phenanthrene as thesole carbon source, showing high phenanthrene elimination(52.9% of the supplied phenanthrene within 20 days). Theaccumulation of 1-hydroxy-2-naphthoic acid and salicylicacid as major phenanthrene metabolites and the capacity ofthe strain to grow with sodium salicylate as the sole sourceof carbon and energy indicated that the S. paucimobilis20006FA possesses a complete phenanthrene degradationpathway. However, under the studied conditions, the strainwas able to mineralize only the 10% of the consumedphenanthrene. Investigations on the cell ability to promotebioavailability of phenanthrene showed that the S. paucimobilisstrain 20006FA exhibited low cell hydrophobicity(0.13), a pronounced chemotaxis toward phenanthrene, andit was able to reduce the surface tension of mineral liquidmedium supplemented with phenanthrene as sole carbonsource. Scanning electron micrographs revealed that: (1) insuspension cultures, cells formed flocks and showed smallvesicles on the cell surface and (2) cells were also able toadhere to phenanthrene crystals and to produce biofilms.Clearly, the strain seems to exhibit two different mechanismsto enhance phenanthrene bioavailability: biosurfactant productionand adhesion to the phenanthrene crystals.