BIODEGRADATION OF ALKYLPYRIDINES BY BACTERIA ISOLATED FROM A POLLUTEDSUBSURFACE

Ten bacterial strains were isolated from alkylpyridine polluted sedime nts 7.6 m below the surface. These strains were able to degrade 11 dif ferent alkylpyridine isomers. Degradation rates depended on number and position of the alkyl group. Isomers with an alkyl group at position 3 were more resistant to microbial attack. Of the 10 strains, 6 isolat es were selected for detailed study. These isolates mineralized the is omers to CO2, NH4+, and biomass. All strains were gram-negative rods w ith a strict aerobic metabolism. Characterization of physiological and biochemical properties revealed similarity between strains. Eeach str ain however, had a limited substrate range which enabled it to degrade no more than 2 to 3 compounds of the 14 alkylpyridine isomers tested. Examination of the genetic variability among cultures with the random ly amplified polymorphic DNA technique revealed high levels of genomic DNA polymorphism. The highest similarity between 2 strains (0.653) wa s observed between 2-picoline and 3-picoline degrading cultures. The m olecular basis of the differences in substrate specificity is under in vestigation.