PRINCIPLES & PRACTICE: ENGINEERED BACTERIAL SOILS
Laura Maria Gonzalez
February 23, 2021
This week we explored the ethics, safety, and security considerations for a biological engineering application or tool and proposed governance policy goals and actions.
I chose to delve into a synthetic biology proposal for the genetic engineering of bacteria to create pressure sensitive soils. The project was proposed by researches at Newcastle University. The goal of this application is to provide an alternative to building foundations through the use of synthetic biomineralization, where engineered cells respond to pore pressure in the environment and synthesize new material to strengthen the soil. This technique could offer a better alternative to building foundations that currently require large excavations and infilling with carbon costly concrete.
Biomineralization is the process by which living organisms produce minerals, often to harden or stiffen existing tissue. Examples of biomineralization include sea shells and bones in mammals and birds. One notable example is the shell of the abalone. Abalone have the ability to bring together calcium and carbonate to form calcium carbonate while making small filaments of protein between the crystals that create a type of adhesive netting that interlaces with the calcium carbonate crystals to provide incredible strength.
The Thinking Soils project explored another type of biomineralization called biologically-induced mineralization. While the abalone has complete control over the crystal morphology, bacteria affect their surroundings to create crystals. They induce CaCO3 formation through the release of Urease, a by-product of bacterial metabolic activity. This can lead to an in crease in pH which causes calcium molecules to bind with carbon and trigger the formation of crystals. The project sought to combine this capacity, with the engineering of bacteria to sense pressure changes in their environment as an extension of material-based design computation.
Bacteria Induced CaCO3
PRIORITIES, TRADE-OFFS, AND ASSUMPTIONS
Thinking Soils Concept Illustration, Dade-Robertson
USE, MISUSE, AND GUIDELINES
Using genetically engineered bacteria to alter soils has wide ranging applications beyond building foundations. For example, biomineralization could be used to develop ceramic alternatives that currently require large amounts of energy to fire at high temperatures ranging from 1700F to 2300F. Biomineralization can also be used to positively affect soil fertility, or combat shoreline erosion.
With these uses in mind I turned to iGem's Safe and Secure Project Design Guidelines as a useful framework for considering potential unintentional/ intentional misuses. The guidelines posed several questions such as:
Who will use the product? What opinions do these people have about your project?
Where will your product be used? On a farm, in a factory, inside human bodies, in the ocean?
If your product is successful, who will receive benefits and who will be harmed?
What happens when it's all used up? Will it be sterilized, discarded, or recycled?
Is it safer, cheaper, or better than other technologies that do the same thing?
Could others use your project in ways other than you plan to cause accidental or deliberate harm.
Red Abalone, CalOceans.org
Ceramics Alternatives, Ceramicartsdaily
Soil Fertility, Nationwide Blog
Foundation Alternatives, Paddy Eng
Erosion Control, Nantucket Chronicle
The questions brought to light three key areas for policy goals including enhancing biosecurity, ensuring equitable use, and protecting environmental health. The table below, adapted from JCVI "Synthetic Genomics: Options for Governance", explores the effectiveness of different proposed policy action through different stakeholders/users.
Corral, Javier Rodriguez, et al. “Study of Bacteria Growth for the Development of Bio-Mediated Soil Improvement Methods.” Proceedings of the 4th World Congress on Civil, Structural, and Environmental Engineering, 2019, doi:10.11159/icgre19.183.
Dade-Robertson, Martyn, et al. “Design and Modelling of an Engineered Bacteria-Based, Pressure-Sensitive Soil.” Bioinspiration & Biomimetics, vol. 13, no. 4, 2018, p. 046004., doi:10.1088/1748-3190/aabe15.
Dade-Robertson, Martyn, et al. “Material Ecologies for Synthetic Biology: Biomineralization and the State Space of Design.” Computer-Aided Design, vol. 60, 2015, pp. 28–39., doi:10.1016/j.cad.2014.02.012.
“Can Biology Build a Better Battery?” Age Of Living Machines: How Biology Will Build the Next Technology Revolution, by Susan Hockfield, W W Norton, 2020, pp. 19–48.
The priorities were also set with a few assumptions in mind including that the technology will be monitorable/trackable. Soils volumes that have engineered bacteria could be detected amongst soil that do not and countries would cooperate with one anther to monitor conditions across borders. Another assumption is the desire of the public to engage with the technology and be a part of open community review sessions. There would need to be incentives to drive engagement over long periods of time, not just when things go wrong. And finally a receptiveness of synthetic biology as a craft skill in the case of individual users such as farmers or ceramicists.