The Biodegradation of Low-molecular-weight Urethane Compounds by a Strain of Exophiala jeanselmei

To further analyze the biodegradation of polyurethane polymers, we investigated the biodegradation of low-molecular-weight N-tolylcarbamate model compounds with structures closely resembling the urethane linkages found in polyurethanes based on tolylene-diisocyanate (TDI). Soil microflora were screened for microorganisms that were able to utilize toluene-2,4-dicarbamic acid, diethyl ester (compound 1) as the sole source of carbon, and the soil fungus Exophiala jeanselmei strain REN-11A was selected as the most effective strain. Several N-tolylcarhamate compounds were used, and it was found that REN-11A was able to degrade compound 1, as well as the related compound toluene-2,6-dicarbamic acid, diethyl ester, very efficiently. Further investigation showed that compound 1 was biodegraded to tolylene-2,4-diamine via the aromatic amine intermediates carbamic acid, (3-amino-4-methylphenyl)-, ethyl ester and carbamic acid, (5-amino-2-methylphenyl)-, ethyl ester.