The logic of carbon substitution: from fossilised life to “cell factories”

This paper examines how researchers in biotechnology reflect on the challenges of turning microbes into what they call “cell factories”. These researchers use the tools of genome editing to harness the biochemistry of single cell organisms, such as bacteria, yeasts and microalgae, and tweak the enzymatic reactions of their metabolism. One research priority is to engineer microbes able to feed on agricultural residues and assemble drop-in compounds to be used in a range of commercial products, from drugs and food additives, to cosmetics, detergents and fuels. To justify financial support for such research, arguments about the need to move away from petroleum as a source of energy and feedstock for chemical synthesis are put forward, underpinned by concerns for climate change, resource renewability and energy security. Drawing on interviews with scientists, we explore what it means for them to make “cell factories” and discuss how they problematise the logic of carbon substitution that orientates their work. Biotechnology is expected to support a shift from one source of carbon, past life gone through slow geological cycles, to a different source of carbon, renewable biomass metabolised by living microbes. As scientists face unhappy cells, recalcitrant plant fibres and unfair competition from fossil-based processes, the promise of carbon substitution tends to be most convincing in the confined space of the lab where faith in biotechnology goes hand in hand with a pragmatic commitment to sustainability. We speculate that the researchers might be failed by the system that biotechnology seeks to (partially) replace, the conditions of which are shaped not around the material constraints of making “cell factories”, but around fossilised life cracked in ever-greater quantities.