Abstract

The first paper describes the ecotoxicological effects of TNT on enchytraeids. TNT was shown to be transformed in the artificial soil used as an exposure matrix, and resulted in enchytraeid mortality and reductions in the number of juveniles as determined by standard tests. The toxicity of TNT and its biotransformation by enchytraeids at the organismal and biochemical levels are described in the second manuscript. Adult enchytraeids were analysed after exposure to TNT in both liquid and soil milieu. TNT-related metabolites were found in enchytraeids after exposure to TNT-spiked artificial (OECD) soil, as well as TNT in liquid. The in vitro experiments showed that biotransformation of TNT in enchytraeids was dependent on the protein concentration and the period of incubation. In addition, TNT biotransformation in vitro was dependent on the sub-cellular fraction, with the 8,000 x g pellet containing the highest activity. Furthermore, the observed TNT-transforming activity in vitro was related to increased bacterial growth found in the potworm homogenate after prolonged periods of incubation. When the antibiotics, tetracycline or streptomycin-penicillin, were added to incubation mixtures, the biotransformation of TNT was inhibited and the bacterial numbers in the potworm homogenate after the exposure time period did not increase significantly. Based on the studies reported in the second manuscript, it is concluded that the transformation of TNT to selected amino-derivatives by enchytraeids is mainly due to bacteria associated with the potworms. A literature review on enchytraeid species, and the biotransformation of TNT by bacteria, is also presented