CATABOLIC GENE PROBE ANALYSIS OF AN AQUIFER MICROBIAL COMMUNITY DEGRADING CREOSOTE-RELATED POLYCYCLIC AROMATIC AND HETEROCYCLIC-COMPOUNDS

The biodegradation of a mixture of several creosote-related compounds, p-cresol, phenanthrene, fluorene, and carbazole was examined in colum ns containing aquifer sands. The aquifer material, itself, had an effe ct on the migration of the test compounds, with p-cresol being retarde d the least, followed by carbazole, then fluorene, and finally phenant hrene. The biodegradation of all the compounds was greatly enhanced by the inclusion of p-cresol (10 ppm) in the substrate mixture. Associat ed with this enhanced degradation was a 100-fold increase in the fetal culturable bacterial population, and increases in the xylE- and ndoB- positive bacterial populations of more than three orders of magnitude. The products of these two genes are involved in the degradation of mo nocyclic and polycyclic aromatic compounds, respectively. In columns t hat did not receive p-cresol, there was no significant change in eithe r the total culturable bacterial population density or the xylE-positi ve bacterial population, but there were significant increases of one t o two orders of magnitude in the ndoB-positive bacterial populations. The results suggest that the ndoB gene probe can detect bacteria capab le of utilizing phenanthrene, carbazole, and possibly fluorene.