michaelm@3comvax.UUCP (05/16/86)
THE WORLD, THE FLESH, AND THE DEVIL Freeman J. Dyson Institute for Advanced Study Princeton, New Jersey III. Biological Engineering I would expect the earliest and least controversial triumphs of biological engineering to be extensions of the art of industrial fermentation. When we are able to produce microorganisms equipped with enzyme systems tailored to our own design, we can use such organisms to perform chemical operations with far greater delicacy and economy than present industrial practices allow. For example, oil refineries would contain a variety of bugs designed to metabolize crude petroleum into the precise hydrocarbon stereo-isomers which are needed for various purposes. One tank would contain the n-octane bug, another the benzene bug, and so on. All the bugs would contain enzymes metabolizing sulphur into elemental form, so that pollution of the atmosphere by sulphurous gases would be completely controlled. The management and operation of such fermentation tanks on a vast scale would not be easy, but the economic and social rewards are so great that I am confident we shall learn how to do it. After we have mastered the biological oil refinery, more important applications of the same principles will follow. We shall have factories producing specific foodstuffs biologically from cheap raw materials, and sewage-treatment plants converting our wastes efficiently into usable solids and pure water. To perform these operations we shall need an armamentarium of many species of microorganisms trained to ingest and excrete the appropriate chemicals. And we shall design into the metabolism of these organisms the essential property of self-liquidation, so that when deprived of food they disappear by cannibalizing one another. They will not, like the bacteria that feed on our sewage in today's technology, leave their rotting carcasses behind to make a sludge only slightly less noxious than the mess they have eaten. If these expectations are fulfilled, the advent of biological technology will help enormously in the establishment of patterns of industrial development with which human beings can live in health and comfort. Oil refineries need not stink. Rivers need not be sewers. However, there are many environmental problems which the use of artificial organisms in enclosed tanks will not touch. For example, the fouling of the environment by mining and by abandoned automobiles will not be reduced by building cleaner factories. The second step in biological engineering, after the enclosed biological factory, is to let artificial organisms loose into the environment. This is admittedly a more dangerous and problematical step than the first. The second step should be taken only when we have a deep understanding of its ecological consequences. Nevertheless the advantages which artificial organisms offer in the environmental domain are so great that we are unlikely to forego their use forever. The two great functions which artificial organisms promise to perform for us when let loose upon the earth are mining and scavenging. The beauty of a natural landscape undisturbed by man is largely due to the fact that the natural organisms in a balanced ecology are excellent miners and scavengers. Mining is mostly done by plants and microorganisms extracting minterals from water, air, and soil. For example, it has been recently discovered that organisms in the ground mine ammonia and carbon monoxide from air with high efficiency. To the scavengers we owe the fact that a natural forest is not piled as high with dead birds as one of our junk yards with dead cars. Many of the worst offenses of humanbeings against natural beauty are due to our incompetence in mining and scavenging. Natural organisms know how to mine and scavenge effectively in a natural environment. In a man-made environment, neither they nor we know how to do it. But there is no reason why we should not be able to design artificial organisms that are adaptable enough to collect our raw materials and dispose of our refuse in an environment that is a careful mixture of natural and artificial. A simple example of a problem that an articial organism could solve is the eutrophication of lakes. At present many lakes are being ruined by excessive growth of algae feeding on high levels of nitrogen or phosphorus in the water. The damage could be stopped by an organism that would convert nitrogen to molecular form or phosphorus to an insoluble solid. Alternatively and preferably, an organism could be designed to divert the nitrogen and phosphorus into a food chain culminating in some species of palatable fish. To control and harvest the mineral resources of the lake in this way will in the long run be more feasible than to maintain artificially a state of "natural" barrenness. The articial mining organisms would not operate in the style of human miners. Many of them would be designed to mine the ocean. For example, oysters might extract gold from seawater and secrete golden pearls. A less poetic but more practical possibility is the artificial coral that build a reef rich in copper or magnesium. Other mining organisms would burrow like earthworms into mud and clay, concentrating in their bodies the ores of aluminum or tin or iron, and excreting the ores in some manner convenient for human harvesting. Almost every raw material necessary for our existence can be mined from ocean, air or clay, without digging deep into the earth. Where conventional mining is necessary, artificial organisms can still be useful for digesting and purifying the ore. Not much imagination is needed to foresee the effectiveness of artificial organisms as scavengers. A suitable microorganism could convert the dangerous organic mercury in our rivers and lakes to a harmless insoluble solid. We could make good use of an organism with a consuming appetite for polyvinyl chloride and similar plastic materials which now litter beaches all over the earth. Conceivably we may produce an animal specifically designed for chewing up dead automobiles. But one may hope that the automobile in its present form will become extinct before it needs to be incorporated into an artificial foodchain. A more serious and permanent role for scavenging organisms is the removal of trace quantities of radioactivity from the environment. The three most hazardous radioactive elements produced in fission reactors are strontium, cesium, and plutonium. These elements have long half-lives and will inevitably be released in small quantities so long as mankind uses nuclear fission as an energy source. The long-term hazard of nuclear energy would be notably reduced if we had organisms designed to gobble up these three elements from water or soil and convert them into indigestible form. Fortunately, none of these three elements is essential to our body chemistry, and it therefore does us no harm if they are made indigestible.