CONSTITUENTS OF AN ORGANIC WOOD PRESERVATIVE THAT INHIBIT THE FLUORANTHENE-DEGRADING ACTIVITY OF SPHINGOMONAS-PAUCIMOBILIS STRAIN EPA505

Sphingomonas paucimobilis strain EPA505 is capable of utilizing many c omponents of coal tar creosote as sole sources of carbon and energy fo r bacterial growth, including fluoranthene and other polycyclic aromat ic hydrocarbons (PAH). During several bioremediation studies, however, we observed that the fluoranthene degradative activity of strain EPA5 05 was inhibited by the presence of undefined creosote constituents. I n practice, integration of a pretreatment step prior to inoculation wi th strain EPA505 was necessary to facilitate the biodegradation of hig h molecular weight (HMW) PAHs. Experiments were thus initiated to dete rmine which compound classes in creosote inhibited fluoranthene metabo lism by strain EPA505. Creosote was fractionated by solvent extraction at various pH, and three chemical classes were examined: acid (phenol ics), base (N-heterocyclics), and neutral (PAH). The mineralization ra te of C-14-labeled fluoranthene and cell viability were examined in th e presence of these creosote fractions at a range of concentrations. T hese studies confirm that strain EPA505 has differing susceptibility t o the effects of the three classes of creosote constituents. The obser ved order of toxicity/inhibition was basic fraction > acidic fraction > neutral fraction. These studies provide engineering guidelines and d efine contamination ranges under which strain EPA505 can be used most effectively as a catalyst in bioremediation (Figure 4).