Needs and strategies for genetic control: municipal wastes.

Municipal wastewater, sludge, and refuse constitute major material flows and area of public concern. Substantial lists of desired improvements in the biological treatment of each waste can be formulated. Many improvements can be brought about by better application of biological and process fundamentals; widespread application of good process control and existing microorganisms is still not a reality. Nevertheless, several improvements seem amenable to genetic control techniques. Whether the genetic control technique involves selection of a novel microorganism or genetic manipulation of conventional or novel microorganisms, two key requirements stand out. First, we must recognize the physiological factor that provides the desired function. Second, we must recombine the genes for the desired function into a microorganism that can thrive in a treatment process. For environmental applications, identifying the physiological effect and an appropriate microorganism are the most critical steps. However, they are probably the least well developed, as biochemists and genetic engineers have concentrated mainly on isolating, recombining, and expressing relatively well known genes into convenient laboratory strains. Because of the many different steps associated with applications of genetic control to municipal-waste treatment, the successful application requires coordination of biochemistry, microbiology, and process engineering. No one discipline has all the requisite tools and insight to do the whole job.