Four microbial strains, isolated from a mixed culture, were used to study biodegradation of 2-nitrotoluene, 3-nitrotoluene, and 4-nitrotoluene individually and in a mixture. The strains were identified as Pseudomonas putida S7, Comamonas testosteroni Pb 50, Rhodococcus sp. Pa 50, and Stenotrophomonas malthophilia K3. The degradation studies were carried out with suspended cells in aqueous media under aerobic conditions and the results were compared with new extensive studies on biodegradation of mononitrotoluenes with a mixed culture isolated from explosives’ contaminated soil from another site. The results showed that (a) the degradation rate of MNTs by the individual strains were of the same order of magnitude as that by the Pardubice mixed culture, (b) the presence of additional N-source positively affected the degradation rate for 3-NT and 4-NT, but adversely affected the degradation rate of 2-NT, (c) no incompletely oxidized dead-end intermediates were found under aerobic conditions, (d) all the cell lines were able to efficiently degrade all the MNTs, even when all were present together, and (e) the degradation rates of individual MNTs in a mixture
were slightly lower than when just one NT was present. Substrate concentration affected degradation rates according to classical substrate inhibition.