Microbial Degradation of TCDD in A Model Ecosystem

Abstract

Microbial degradation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was studied by using pure culture isolates of microorganisms, terrestrial and aquatic model systems, and an outdoor pond. In each case metabolic activities were recognized by the appearance of metabolic products from ¹⁴C-TCDD. In the outdoor pond the apparent half-life of TCDD was in the order of one year, recoveries of TCDD after 12 and 25 months being 49.7 and 29.4 percent, respectively. In model systems metabolic activities on TCDD were stimulated by the addition of general nutrients such as glucose, bactopeptone and mannitol yeast. The two microbial isolates, Bacillus megaterium and Nocardiopsis sp., were found to degrade TCDD. The most important factor found to promote their metabolic activities was the nature of carrier solvent for TCDD. In this regard ethyl acetate gave the best results under the experimental conditions.