Anaerobic biotransformation of 2,4-dinitrotoluene with ethanol as primary substrate: Mutual effect of the substrates on their biotransformation

The effect of the initial concentration of 2,4-dinitrotoluene (DNT) on its biotransformation and on the microbial utilization of ethanol was investigated. The culture used in this study was acclimated in a continuous flow laboratory fermentor with 2,4-DNT and ethanol as substrates under strict anaerobic conditions at 35°C. Biochemical Methane Potential (BMP) tests were conducted in an anaerobic respirometer, and the acclimated culture from the fermentor served as the inoculum. 2,4-DNT was completely transformed to 2,4-diaminotoluene (DAT) under anaerobic conditions. Two intermediates, 2-amino-4-nitrotoluene (2-A-4-NT) and 4-amino-2-nitrotoluene (4-A-2-NT), were found during the biotransformation. 2,4-DNT inhibited its own biotransformation as well as the acetogenesis of ethanol. The extent of the inhibition increased with the increase of the initial concentration of 2,4-DNT. Propionate was formed during the fermentation of ethanol without 2,4-DNT or with low initial concentrations of 2,4-DNT. Higher initial concentrations of 2,4-DNT caused a decrease in the extent of formation of propionate with acetate production being favored.