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 fermenter with 2,4-DNT and ethanol as substrates under strict anaerobic conditions at 35 degrees C. Biochemical Methane Potential (BMP) tests were conducted in an anaerobic respirometer, and the acclimated culture from the fermenter 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.