Anaerobic biotransformation of 2,4-dinitrotoluene with ethanol, methanol, acetic acid and hydrogen as primary substrates

2,4-dinitrotoluene (DNT) was anaerobically reduced to 2,4-diaminotoluene (DAT) with either ethanol, methanol, acetic acid or hydrogen as the primary substrate. Biochemical methane potential (BMP) tests in an anaerobic respirometer indicate that 2,4-DNT was reductively biotransformed to 2,4-DAT via 4-amino-2-nitrotoluene (4-A-2-NT) or 2-amino-4-nitrotoluene (2-A-4-NT) with either methanol, acetic acid or hydrogen as the primary substrate under anaerobic conditions as it was with ethanol as the primary substrate. However, the rate of 2,4-DNT biotransformation was much higher with ethanol as the primary substrate than that with either methanol or acetic acid as the primary substrate. Ethanol-enriched anaerobic culture was much better for the reductive biotransformation of 2,4-DNT than methanol- and acetate-enriched cultures when hydrogen was used as the primary substrate. Biotransformation of 2,4-DNT was not observed without any primary substrate. 2,4-DNT was not completely transformed to 2,4-DAT in the BMP tests unless enough ethanol was initially added to produce twice or more the hydrogen stoichiometrically needed for the reductive biotransformation. The addition of a high concentration of ethanol accelerated the reductive biotransformation of 2,4-DNT. The presence of 2,4-DNT, 4-A-2-NT and 2-A-4-NT inhibited the methanogeneses of methanol, acetate and hydrogen, as they did on the acetogenesis of ethanol.