Abstract
Polymeric materials are widely used in engineering facilities for protection against corrosion and growth of microorganisms. They are known to be susceptible to microbial degradation, but few investigations have examined both the basic microbiology and the biochemical mechanisms of degradation involved. An enrichment culture was established using water-soluble polyurethane as the sole source of carbon and energy and soil as an inoculum. In subsequent enrichment transfers in minimum salt medium supplemented with polyurethane, growth of the bacterial consortium was observed, indicating degradation of the polymer. After isolation and purification of the dominant bacterial species from the consortium, two bacterial isolates were obtained and both of them were aerobic and Gram-positive rods. One of the bacteria was found to be responsible for the degradation of polyurethane and the 16S rDNA was sequenced. This isolate was found to be closely related to Rhodococcus species with 99.8% similarity and was designated as Rhodococcus sp. H07. Degradation of a polyester-polyurethane aqueous suspension was confirmed using electrochemical impedance spectroscopy with the pure strain of bacteria as the inoculum. Esterase activity was correlated with the growth of the Rhodococcus sp. H07 when the aqueous polyester-polyurethane suspension was used as the sole source of carbon and energy. Results suggest that polyurethane-degrading bacteria are common microflora in the natural environment and they pose a challenge to the protection of engineering surfaces.
