The fundamental value of Biocrafter, sustainability, was central in the early phases and throughout our project, as we were drawn to a goal of reducing the environmental impact of the construction industry.

Concrete makes up for 8% of global CO2 emissions, a fifth of the carbon footprint of the construction industry which is worldwide responsible for 40% of greenhouse gas (GHG) discharge. This contribution is broken down further in Figure 1, which shows how the majority of CO2 emissions associated with concrete are derived from cement production. The UK’s Annual Cement Demand is 15.2 million metric tons (188% of UK Cement Production Capacity) [1].

To decarbonise the construction industry, it would be desirable to phase out Ordinary Portland Cement (OPC) production plants that operate with coal, fossil fuel and non-renewable gas as per COP26 and Atkins Engineering Net Zero Decarbonomics approach [2, 3]

In line with this goal, we focussed on designing an environmentally sustainable bio-alternative to cement, by engineering a strain of Bacillus subtilis with enhanced biomineralisation properties, to ultimately aide in the formation of a biomaterial capable for use in construction.

Figure 1. A breakdown of the greenhouse gas emissions associated with contemporary, concrete-based construction. Taken from a 2020 paper by Habert et al. [4].

During the course of the summer we not only considered sustainability when designing the project, but also moral and social values. Our core values and how we addressed them are summarised in:

Table 1. The core values of the UCL iGEM team, Biocrafter, and why they matter.

To ensure our project was safe and responsible, we consulted with various experts, for example Dr Brenda Parker who is Programme director of the Bio-Integrated Design at UCL's The Bartlett School of Architecture and Biochemical Engineering Department, and with Rollin James who works at ‘okam wrks’, a company ‘primarily focused on harnessing the self-replicating wonders of mycelium in order to create 1:1 substitutes for materials that have historically led to deforestation’. We consulted with stakeholders regarding biosafety, biocontainment, material property safety, durability and price and implemented their feedback into our engineering cycles. Through this integration of feedback (described in detail in Integrated Human Practices), we were able to tailor our project to ensure its responsible, safe, and can be successfully translated into the real world.

With our supervisors, who have expertise in Synthetic Biology we discussed the biosafety aspects of a ‘living’ brick material versus a ‘non-living’ brick. One approach we thought of to reduce risks is integrating sterilisation into our manufacturing process in a way which does not negatively impact product quality. Included in this was baking/drying bricks at high temperatures or using lysed cells in a powdered form where ready mix product was to be distributed in bags.

To ensure our brick is safe for construction purposes we consulted Luke Heaton and discussed the structural safety aspects of integrating biomaterials. He suggested that initial use cases should be in contexts which require less robust mechanical qualities to the product (e.g. home Do It Yourself (DIY) such as sheds or patios). This could inform longer term product development of a material which could adhere to strict structural regulatory frameworks and be deemed safe for use in larger scale commercial projects.

To engage local communities, we have run an extensive questionnaire in hardware stores worldwide with 200 customers in Western Europe (UK), Central Europe (Slovakia, Austria, Germany), Eastern Europe (Romania), Asia Pacific (Taiwan), North America (USA) and discussed safety aspects with customers in stores (Figure 2A). The findings of our survey were similar between regions and revealed that most people are aware to some extent of the carbon intensive nature of the construction industry and were would like to see a biomaterial alternative (Figure 2B left). People were not opposed to the idea of genetically modified organisms in buildings and had limited concerns about the presence of active or inactive non-pathogenic microbial species in the material (Figure 2 B right, C and D). They said they would purchase ready-mixed formulations at the same price or slightly higher (10-15%) than traditional ready-mixed concrete or Ordinary Portland Cement (OPC) (Figure 2E). It seemed that younger people were more accepting of the premise of synthetic biology being used to tackle climate change (age data not shown).

A

B

C

D

E

Figure 2: A. Sam and Vero carrying out a survey with local customers at Hornbach in Slovakia (left and centre). Stefan carrying out a survey with local customers at Dedeman in Romania (right). B-E Survey results of 200 global customers.

As a ‘climate crisis’ track iGEM project, the primary way in which Biocrafter was intended to be a force for good was through reducing the CO2 emissions associated with concrete (in replacing it with a sustainable biomaterial). To determine if our concept could achieve that, we took three approaches:

The first two items on this list are largely addressed above under ‘Communities / Resources’. Experts including Dr. Brenda Parker (UCL Bio-Integrated Design), Prantar Tamuli (PhD candidate researching biomaterials), Rollin James (Okam Wrks), and Luke Heaton (University of Oxford, biomaterials start-up founder) all supported the potential viability of our project as a directed effort to achieve our environmental aims. A literature review (see our ‘Guide to Biomineralisation Projects’ under Contributions) also demonstrated a wider scientific belief in the green credentials of the technology behind our project, and our global survey on construction biomaterials allowed us to recognise how public opinion could facilitate or hamper the adoption of our products.

To appreciate the scientific viability of our project ourselves and understand whether it could support our environmental aims, we had to develop a means to quantify the environmental impacts of the materials we were studying and creating. Our goal was to assess the environmental impacts of traditional Portland cement production and, in doing so, create a framework which could be applied to study those of our own material.

Life Cycle Assessment (LCA)

Life cycle assessment (LCA) is a procedure employed to assess the environmental impacts associated with the manufacture a commercial product. It is done via software which draws on databases containing profiles of the raw materials which are used to manufacture products. Impact assessment algorithms quantify the overall impact of production processes, including the effects of raw material extraction and the use of e.g. electricity.

Our aims within human practices drove us to develop an LCA which could independently verify the emissions attributed to the production of Portland cement. Portland cement is a staple of modern construction, and the widely available data on the environmental profile of the product meant that we could check the results of our modelling against reliable sources (see Figure 1 above for an example of some of this data).

Once we knew we could create realistic life cycle assessments, we were then able to repeatedly model our own proposed processes for the creation of our biomaterial, refining them progressively with the results of each LCA. This iteratively informed the technical development of our product and proposed processes, and as such we felt it was more suitably included under ‘integrated human practices’ below. However, our initial assessment of Portland cement stood independently as an earlier contribution to the project which gave us confidence that our environmental goals within human practices could be achieved.

Figure 3. Image depicting LCA. Credit: Rochester Institute of Technology, taken from https://www.rit.edu/sustainabilityinstitute/blog/what-life-cycle-assessment-lca

LCA for Portland cement:

To independently verify Portland cement production in line with our future bioprocess we first conducted a LCA analysis on the traditional manufacture process:

The software we used was OpenLCA using the Ecoinvent database and impact assessment using ReCiPe2016 scoring.

Overview of the traditional process we aim to mitigate (shown in Figure 4):

Figure 4: (Left) The traditional Portland cement Process Flow Diagram (PFD) with values of materials to produce 1000kg of cement. (Right) The key components of Portland cement and where they are introduced within the manufacturing process.

Figure 5: Pictures from Biocrafter onsite visit to a cement plant in Romania

The key output of our first LCA was that 1.27 ± 0.02 of CO2 is released per kg of cement produced. This range of values reflects that different facilities rely on varying fossil fuels in their furnaces.

This LCA was the starting point of calculating the carbon mitigation of our future processes, later shown under integrated human practises.

LCA methodology:

LCA Software: OpenLCA

Database: EcoInvent (entries provided by Dr Brenda Parker, Biochemical Engineering, UCL)

Impact assessment method: ReCiPe 2016 Midpoint (H)

Approach: cradle-to-gate

Functional Unit: 1 kg binding material

Due to the complexity of our project in producing a ‘living’ brick with sufficient biomineralisation properties, challenges we faced in the laboratory, and our engineering cycles, our project underwent several iterations. Each change in our project was done to ensure the safety and responsibility of our project for the wider community and world. To aide us in achieving this, we integrated and acted upon the feedback received through our surveys, advice and guidance provided by our supervisors and various academics, as well as leading experts in the fields of biomaterials, civil engineering, construction, and synthetic biology.

The team was inspired by living building material developed by researchers at Colorado University Boulder [1]. Schrubar et. al. used biomineralising cyanobacteria to replace cement in a construction material, further they showed that the cells survive in material for up to 30 days. And so, the first iteration of the project was born: Engineering cyanobacteria to enhance their biomineralisation potential.

How Human Practices work informed and shaped our project:

Our project was informed at every level through reaching out to industry and academic experts in the field of biomineralisation and biomaterials.

Academic Input

Dr. Sadjad Naderi, who is an expert in mechanical and structural modelling of concrete, and who computationally focusses on modelling 3D microstructures, has discussed the development of mesoscopic FEA modelling of our material with us. Although we have tried to implement this on our materials, it did not work, however we learned new stress and strain testing protocols that could be used to quantify properties of our material.

Prantar Tamuli, a PhD candidate at UCL was consulted with throughout the project for his expertise in biomineralization and biomaterials. He discussed the feasibility of including multiple enzymatic biomineralisation pathways in the same organism with us and educated us on the strengths and weaknesses of each. He guided our early brainstorming sessions by highlighting the value of our initial proposal to combine mycelium and hydrogel within our biomineralized material, a technique which showed theoretical promise but had been little explored in literature. Prantar’s expertise also guided our experimental design and allowed us to select the relevant assays required to quantify the biomineralization potential of our organism. Biominerilising cyanobacterial was also kindly gifted by Prantar, where we collaboratively shared data.

We also attended the UCL Bio-Integrated design showcase focusing on biologic material in design. Dr Brenda Parker, the co-head of the Bio-ID group, advised us on how the desired form of buildings which incorporate our material should be identified, we therefore used her advice to guide our product development. She also identified that it was important to consult with an expert on the chemical equilibria underlying carbonic anhydrase activity which impacted our modelling approach. Some of the projects which we saw at the Bio-ID exhibition are shown in Figure 7.

Industrial Perspective

We connected with Professor Will Schrubar, who published the paper that initially inspired our research project. He connected us with Rollin James of okom wrks. Okom wrks is developing a biomaterial mycelium composite from fungus and hemp. His input and expertise allowed us to optimise our method of mycelium introduction into our materials, and we subsequently altered our experimental design to mix our aggregated bacteria prior to introduced it to shredded live mycelium. Rollin further gave us suggestions on the measurement of tensile and compressive strength, all ideas we implemented into our engineering cycles to contribute to our final proof of concept.

Further to this, reached out to ARUP, a global architecture firm known for their ‘mycelium tower’. We were put in touch with Luke Heaton, the creator of poly mycelium biomaterial (POMB), which turns agricultural waste into mycelium growth medium for large scale production of mycelium-based biomaterials. Luke gave us theoretical insights on the inclusion of mycelium in the material and educated us on the safety and legislative considerations surrounding bringing a construction biomaterial to market.

Figure 6: The Living and ARUP collaborative Mycelium Tower, displayed in New York, US.

Through these conversations, we have grown to appreciate the legal landscape of new materials and timescales for regulatory endorsement. Our biomaterial is a novel product on the construction market and it has to comply with building regulations such as the Regulation (EU) No 305/2011 stipulating conditions for the marketing of construction products (https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32011R0305).

As our product will also have to be certified as a GMO application, feed back from Luke Heaton, and the Bio-ID group informed our process for the sterilising heat treatment of our BioBrick and the proposed timeline for adoption and implementation of our products (the time required to gain legislative approval for structural integrity is discussed on the proposed implementation page).

Figure 7. Exhibits on display at the June 2022 UCL Bio-Integrated Design exhibition. (Above) Prantar Tamuli showcases his biomineralized biomaterials. (Below) Various organic materials on display, some of which then prompted the UCL iGEM project to incorporate alternative aggregate materials into prototyping such as sawdust. Images used with permission from UCL Bio-Integrated Design [7] and Prantar Tamuli.

See communities section of human practices above for details and results of the survey.

We noticed an increasing number of teams within the iGEM community were working with biomaterials, therefore we produced a survey, to gauge the opinion of the wider public on the use of genetic engineering biomaterials in construction. This surveyed over 200 consumers shopping at hardware stores across Western Europe (UK), Central Europe (Slovakia, Austria, Germany), Eastern Europe (Romania), Asia Pacific (Taiwan), and North America (USA). Their opinions on safety and product pricing informed how we planned to manufacture and implement our product, and their opinions directed our strategy for education and outreach. The main concerns expressed were the ethical implication of our projects, safety, affordability, and more general negative association with engineered organisms. As a result, we implemented more topics related to that area in our outreach activities to increase the awareness when it comes to safety of genetically modified organism.

To increase awareness, we ran a biomaterials workshop we ran at a high school in Kent, UK, we explained the prevalence of microbial life in everyday settings to students. Following this, we then highlighted the differences between wild type E. coli / B. subtilis and our engineered strains, building a ‘bottom up’, scientific understanding of how our microbes pose few risks beyond those associated with ubiquitous wild species. This was an approach we also took with our children’s book, looking to increase scientific understanding and literacy to alter perceptions regarding the safety of recombinant technologies. A less obvious aspect to this educational resource is that the audience being targeted is not only young children but their parents, who will read the book books aloud to their kids. In a further effort to respond to our survey results, we also created a lab safety game which has been played online over 1000 times at the time of writing. As well as educating others on how to operate safely in a laboratory context, this was designed to showcase the safety measures that go into developing a GM organism to a non-technical audience.

Please note that the above text is only meant to show how our survey informed our education and outreach efforts. The educational resources themselves are not part of human practices and form our submissions towards the education award.

Finally pulling together what we has learnt through our Human practises, we designed a Bioprocess and products to function as a drop-in replacement for cement.

The final bioprocess we developed was a culmination of the of the wet lab results, proof of concept brick development and input from industrial advice on implementation.

We brought this together and developed a proposed bioprocess necessary to meet 1% of the UK annual demand for cement to test our product on non-residential projects for eventual certification. Based on the inputs found during the project we set the parameters of the LCA and found that our process produced less CO2 per bag compared to the traditional Portland cement by orders of magnitude (see Figure 10 below).

How is the LCA an Example of 'Integrated' Human Practices

Figure 8. The interaction and interdependance between the LCA and other areas of our projecrt

The iterative design process behind the LCA model was intrinsically interlinked with our process and product design as it is these technical decisions that affect the LCA. Through this relationship, it had a large impact on many areas of the project, as is shown in Figure 8. Using different feed streams (e.g. wastewater instead of fresh water), altering process unit operations (e.g. using spray drying rather than freeze drying), incorporating alternative aggregate materials into our prototypes (e.g. sawdust) and figuring out where flows could be recycled (e.g. redistilling process broth to capture unused calcium salts) are all examples of the design decisions influenced by the LCA.

The LCA informed the proposed implementation of the two finished formats for our product (see proposed implementation page). It highlighted that, environmentally speaking, BioBrick was the preferable format. Thus, our timeline for adoption sets out how, for incorporation of our material into commercial construction in the long term, we will have to make use of infrastructure arising to support a growing global bioeconomy. Multi-purpose, distributed manufacturing hubs will span geographies and allow for manufacturing of BioBrick in proximity to construction sites, minimising the amount of emissions caused by transportation. These bioprocessing facilities will be ubiquitous throughout urban and rural areas, as chemicals and goods will be produced on-demand by consumers who download and print the DNA which gives microbes the ability to make their substance of interest. An agitated bioreactor alongside basic downstream processing equipment (e.g. filters, centrifuges) will be able to support the manufacture of an array of products.

Definitions to Interpret LCA:

BioBag is a product which is functionally similar to bagged cement. It contains dried B. subtilis, along with the components necessary to support bio-cementation (i.e. urea, calcium chloride, sodium alginate, and cumate). This mixture would be combined with water and coarse aggregate (typically sand) by the consumer to form a wet intermediate which will then be moulded and set, forming a solid material.

BioBrick is a finished, solid material, produced in-house and then distributed to consumers. It would be directly incorporated into construction projects and, as such, no special equipment or training would be needed for its use.

Ordinary Portland Cement (OPC): Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete. It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker, grinding the clinker, and adding gypsum. Ready-mixed cement bags are mixed with aggregate like sand and water and used as conventional building material.

Processed Design and Flow Diagrams

Through our prototype brick development we found an ideal ratio of hydrogel ingredients and aggregates to give a base line strength before bio minerilisation by engineered B. subtilius

We brought this together in to our proposed bioprocess We designed the bioprocesses which were analysed in our LCA such that they cover 1% (80,500 metric tons per year) of the UK’s annual cement production, including an excess of 9000 metric tons annually to account for product loss or batch failure. The processes are depicted as process flow diagrams in Figure 7.

The bacteria would be mixed as a binder with other components (urea, calcium chloride, hydrogel) to warrant the intended function through scaffold formation, cell arrangement and self-healing capabilities. Modified microorganisms on their own do not provide a suitable level of cementation without adequate amounts of support. Mixing would be done in appropriate ratios reflecting construction industry standards for enhanced integration in existing distribution networks and production frameworks, as well as compliance with regulatory policies.

Figure 9. The planned processes for manufacturing BioBag (above) and BioBrick (below), represented as a process flow diagrams. Relevant feed streams are included alongside material recycling flows. ‘Hydrogel SA/CA’ denotes hydrogel based on either sodium alginate or carboxymethyl cellulose. ‘MF’ denotes microfiltration. ‘RO’ denotes reverse osmosis.

LCA Results:

Our main goal was to assess the environmental impact(s) of traditional Portland cement production compared to two designs of Biocrafter biomaterials called BioBag and BioBrick.

The two graphs in Figure 10 summarize the main findings of the LCA analysis between the two bioprocesses for BioBag and BioBrick and average/combined Ordinary Portland Cement OPC production (OPC). Average production of OPC refers to equal amounts of coal, oil and gas being used, whereas 'OPC combined' still uses a mixture of the fossil sources, but not in equal amounts/ratios.

Both BioBag and BioBrick have a substantially lower contribution to global warming compared to Ordinary Portland Cement because of a minimized carbon footprint. To be more specific, BioBag produces up to 54% less CO2 than average OPC and up to 85% less CO2 compared to the combined OPC. Conversely, BioBrick produces up to 92% less carbon dioxide than average OPC and up to 97% less CO2 compared to the combined OPC.

BioBag has a greater carbon footprint than BioBrick since the former involves centrifugation and spray drying of the bacteria, these are operations that are energy demanding. A similar pattern can be seen for Particle Matter formation: BioBag has 95% less GHG emissions than average OPC and produces up to 98% less GHG compared to the combined OPC. BioBrick has 99% less GHG emissions than average OPC and combined OPC. In terms of mineral resource scarcity, BioBag depletes 55% less sand than average OPC and consumes 85% less sand compared to the combined OPC. BioBrick depletes 94% less sand than average OPC and consumes 98% less sand than combined OPC.

Both bioprocesses are however, are water intensive, which may be because these rely on steam sterilisation (as we learnt from Dr. Brenda Parker) and cleaning of large-scale fermentation vessels. To achieve the right pressure and temperature for microbial spore inactivation, water must be heated to a supercritical state. Then, bioreactor cleaning involves dilute solutions and several rinsing steps, which again has an aggressive water consumption rate. BioBag has a larger water requirement than BioBrick since the former involves centrifugation that needs a diluted feed for optimized clarification and improved solid particle settling due to a density gradient.

Figure 10: OPC AVG = Average production of OPC refers to equal amounts of coal, oil and gas being used, whereas OPC combined still uses a mixture of the fossil sources, but not in equal amounts/ratios. Global Warming pertains to global carbon emissions leading to climate change, Mineral Resource Scarcity is connected to riverbank sand mining, Water Consumption models the contribution to freshwater scarcity and Particle Matter (PM) formation relates to air pollution and deleterious health issues associated with inhalation and skin absorption. PMs as airbourne particles get smaller and smaller on the micrometre scale, which makes it easier to be disseminated. PM2.5 and PM10 are the most prevalent in all technoeconomic sectors, including industrial manufacturing, especially relevant in the concrete making context, where air containment and recirculation is not as regulated as in a biopharmaceutical context.

What we Learned

Our LCA showed that our final process/product designs further outperformed Portland cement in when considering other environmental metrics. These include the release of carcinogenic particulate matter (pm2.5 and 10, see Figure 5) and the contribution of the process to mineral resource scarcity. We did find that our process was more water intensive than Portland cement production however, and these results will help guide the iterative development of the bioprocess going forwards. We aim to mitigate the effects of water-intensive production by locating manufacturing facilities in regions of low water stress, alongside potentially employing single use bioprocessing technologies, which do not require the large volumes of (high temperature) water required to repeatedly sterilise clean-in-place vessels. Further to this, our processes minimise freshwater usage by drawing from wastewater feed streams and redistilling spent process water (also recovering unused calcium salts).