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Metabolic potential and phylogenetic analysis of phenol-degrading bacteria cultured from freshwater sediment phenol-enrichment microcosms.
Hardwick, Elaine*,1, McCormick, Warren1, Tomforhde, Paul, 1 Minnesota Sate University, Mankato, Mankato, MN
ABSTRACT- Phenol is a structural component found in many naturally occurring complex carbon compounds (e.g., humic acids) and is also commonly used as an organic solvent in industry. Pollutional inputs of phenol into freshwater systems have become an increasing problem and there is interest in finding indigenous organisms that can degrade phenol. Using freshwater sediment microcosms amended monthly with 0.1% (v/v) phenol for a period of one year, indigenous bacteria capable of using phenol as their sole carbon and energy source were isolated and cultured. Analyses determined that these degraders were metabolically versatile (e.g., fermenters, denitrifiers) and were also highly resistant (71%) to six different antibiotics when compared to culturable non-degraders (37%). Phylogenetic analysis resulted in at least two previously unidentified species, one with 96% similarity to Rhodococcus coprohilus strain JCM 3200, and the other with 96% similarity to Rhodococcus roseus . This study suggests that indigenous bacteria may serve as a reservoir of antibiotic resistance genes that could be transferred to other bacterial populations (e.g., human commensals). Yet, these bacteria are capable of anthropogenic pollutant degradation and thus represent a potential "natural" source of organisms for use in bioremediation.
KEY WORDS: phenol-degraders, culturable bacteria, antibiotic resistance, phylogenetic analysis