Trace the products we buy and use every day—from plastics and fabrics to cosmetics and fuels—back to their origins, and you’ll find that the vast majority were made using stuff that came from deep underground. The factories that make the products of modern life do so, by and large, out of chemicals of various kinds. And those chemicals come from plants powered primarily by fossil fuels that transform feedstocks—also mainly petrochemicals—into myriad other compounds.
It would be much better for the climate, and possibly better for the global economy as well, to make many of the chemical inputs to industry from living organisms instead of from oil, gas, and coal. We already use agricultural products in this way, of course—we wear cotton clothes and live in wooden houses—but plants are not the only source of ingredients. Microbes arguably offer even more potential, in the long term, to make inexpensive materials in the incredible variety of properties that we now take for granted. Rather than digging the raw materials of modern life from the ground, we can instead “brew” them in giant bioreactors filled with living microorganisms.
For bio-based chemical production to really take off, it must compete with conventional chemical production on both price and performance. This goal now seems within reach, thanks to advances in systems metabolic engineering, a discipline that tweaks the biochemistry of microbes so that more of their energy and resources go into synthesizing useful chemical products. Sometimes the tweaks involve changing the genetic makeup of the organism, and sometimes it involves more complex engineering of microbial metabolism and brewing conditions as a system.
With recent advances in synthetic biology, systems biology, and evolutionary engineering, metabolic engineers are now able to create biological systems that manufacture chemicals that are hard to produce by conventional means (and thus expensive). In one recent successful demonstration, microbes were customized to make PLGA [poly(lactate-co-glycolate)], an implantable, biodegradable polymer used in surgical sutures, implants, and prosthetics, as well as in drug delivery materials for cancer and infections.
Systems metabolic engineering has also been used to create strains of yeast that make opioids for pain treatment. These drugs are widely needed in the world, and in particular in the developing world, where pain is insufficiently managed today.
The range of chemicals that can be made using metabolic engineering is widening every year. Although the technique is not likely to replicate all of the products currently made from petrochemicals, it is likely to yield novel chemicals that could never be made affordably from fossil fuels—in particular, complex organic compounds that currently are very expensive because they must be extracted from plants or animals that make them in only tiny amounts.
Unlike fossil fuels, chemicals made from microbes are indefinitely renewable and emit relatively little greenhouse gas—indeed, some could potentially even serve to reverse the flow of carbon from Earth to atmosphere by absorbing carbon dioxide or methane and incorporating it into products that are eventually buried as solid waste.
As biochemical production scales up to large industrial use, it will be important to avoid both competing with food production for land use and also accidental releases of engineered microorganisms into the environment. Although these highly engineered microbes will likely be at a great disadvantage in the wild, it’s best to keep them safely in their tanks, happily working away at making useful stuff for the benefit of humanity and the environment.
This is part of a series on the top 10 emerging technologies of 2016, developed in collaboration with Scientific American.
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