The study of microbial biotransformation reactions has focused largely on chemical substances of particular interest to humans. The terms ‘biotransformation’, ‘biocatalysis’ and ‘biodegradation’ have been used almost interchangeably, depending on the interest of the people studying the reactions. In this issue, there are excellent descriptions of biodegradation reactions for the biotransformation of potentially toxic compounds. Examples include the nitroaromatic explosives, such as 2,4,6-trinitrotoluene (TNT), the PCBs, and the phosphotriester pesticides and nerve agents. In the case of PCBs, Abraham et al. point out that these materials have apparently been co-opted as final electron acceptors in anaerobic sediments where electron
acceptors are probably deficient. This represents a specific adaption to the chemical environment. With TNT, Heiss and Knackmuss (pp 282–287) tell a somewhat different story of apparently non-specific reduction of nitroaromatic explosives to generate intermediates that react to oligomerize and condense with soil organic material. Whatever the intent of the soil microbes, these reactions have potential utility by rendering the compounds less leachable and
bioavailable and, thus, can be construed as environmental detoxification. In the case of synthetic phosphotriester compounds, microbial hydrolysis offers a dramatic reduction in toxicity and, thus, has broad applications. Phosphotriester pesticides such as paraoxon have been shown to be excellent substrates for the phosphotriesterase from Pseudomonas diminuta, which has been extensively studied by Raushel (pp 288–295) and is the subject of the review on this topic in this issue. The review points out that the most toxic of the synthetic organophosphate compounds are military nerve agents such as soman and VX.