Anaerobic and Aerobic Transformation and Biodegradation of TNT
Many studies on the microbial metabolism of nitroaromatic compounds have used pure cultures of aerobic microorganisms. In many cases, attempts to degrade nitroaromatics under aerobic conditions by pure cultures result in no mineralization and only superficial modifications of the structure. However, aerobic mixed culture systems developed in the Center and properly manipulated result in the transformation and mineralization of TNT. The mixed culture systems require a cosubstrate and unique operational startegies to achieve efficient biodegradation of TNT. Another option for the biodegradation of TNT and nitroaromatics is under anaerobic, sulfate-reducing conditions. In this instance, we have found that the nitroaromatic compounds undergo a series of reductions with the formation of amino compounds. For example, trinitrotoluene under sulfate-reducing conditions is reduced to amino derivatives and then further metabolized to toluene by pure cultures. If an anaerobic mixed culture is utilized breakdown to organic acids occurs with the potential for mineralization of the nitroaromatic. These microbial processes provide innovative biological solutions to the disposal of nitroaromatics.