Moving upstream in synthetic biology

TLDR

Astera is seeking short statements of ideas for innovations that might help synthetic biology scale. We will publish these statements on our website, and will award $1,000 bounties for the five best ideas.

OVERVIEW

This is an exciting time for synthetic biology: We’ve advanced past proof-of-concept for ways to replace traditional solutions in a wide variety of domains (climate, food, therapeutics, cosmetics, manufacturing, terraforming, etc.) using more planet- and human-friendly methods. There’s demonstrable and growing demand for innovative synbio solutions.

Much of this work, however, has hit the same wall: scalability. Many factors together cap progress, including limited and suboptimal organismal chassis, fermentation hardware optimized for a narrow set of options, and long timelines. Even where they are technologically and environmentally superior, it remains difficult for many synbio solutions to achieve cost parity with traditional alternatives. This has led to companies winding down and investor interest cooling.

Astera aims to identify “upstream” interventions — such as more diverse host or source organisms that are optimal for scaling, alternative fermentation or growth approaches, and high-risk but creative scaling strategies — that might help synthetic biology scale cost-effectively, and therefore unlock new applications and funding opportunities. We are sourcing ideas from the community as one early step in an effort to support innovation in this domain.

We are seeking short (from a couple sentences to one page) statements that describe a technological bottleneck limiting innovation in synthetic biology, along with a proposed solution. What novel organisms, hardware, software, and other technology would allow synthetic biology to scale in domains where it currently struggles to do so? What technology would we build to maximize synbio’s potential if we were starting the field from scratch?

The main objectives of this call are to:

We aim to identify speculative, “pre-competitive” ideas that can “lift all boats” in synthetic biology. We believe that, in addition to the goals above, sharing these ideas widely has the potential to help them find founders and funders. Accordingly, we will publish submitted statements on our website, and will award $1,000 bounties for the five best ideas we receive.


To determine our five $1,000 bounty winners, each submission was anonymized and then scored by three reviewers, using a rubric that incorporated four criteria, listed in order of descending weight:

  1. Relevance and Impact: Does the idea address the specific scaling challenges outlined in the call? Does the idea have the potential to significantly advance the field of synthetic biology?
  2. Feasibility and Tractability: Is the proposed solution technically feasible and tractable with effort? Can specific actions be taken to implement it?
  3. Novelty and Neglectedness: Is the idea innovative? Does it explore an area that is currently underexplored by others in the field?
  4. Clarity and Simplicity: Is the idea well articulated and easy to understand?

Following this procedure, these five ideas were selected to receive bounties – congratulations to the winners!


Winning Statements

  • Anonymous

    Fermentation of Gaseous Carbon Feedstocks

    However, if the goal is meaningful displacement of petroleum, the continued focus on crop-based sugar may be misdirecteFermentation of gaseous carbon feedstocks could be the catalyst to sustainability that has so far eluded sugar-based fermentation. In particular, the environmental thesis of microbial synthetic biology has revolved largely around the up-conversion of carbon-sequestering plant starch. d. Its vastly lower abundance vs. petroleum, inherent conflict with the food supply, and questionable benefit (once petroleum-derived fertilizers and total energy use are considered) are among the well-documented critiques. An alternative that, in fact, exists on the scale of fossil carbon and directly mitigates atmospheric carbon is that of CO2, CO, and CH4 emissions themselves. Capture and upgrading of otherwise released emissions from anaerobic digestion (e.g., municipal solid waste) and industrial production (e.g., steel, cement, bioethanol) would decarbonize over 20% of the US carbon footprint. As important, the ability to utilize gaseous feedstocks would provide a long-sought, and easily scalable, pathway for mobilizing the 1–1.5B tons of potentially available lignocellulosic biomass. Despite the prospects of displacing almost 50% of US petroleum consumption, lignocellulose (e.g., energy crops, forestry and agricultural residues) remains largely untapped due to deconstruction challenges. Pretreatment and hydrolysis into monosaccharides are still sufficiently complex such that agricultural sugar continues to be the more competitive option. In contrast, gasification of biomass into syngas (CO2/CO/H2) is a mature technology that could, for example, be added to existing thermal plants at a reasonable cost of $400–600/kW. However, other than the biotech LanzaTech (syngas-to-ethanol), few others have invested in tools and methods for commercial-scale gas fermentation. Moreover, their technology remains proprietary. Therefore, greater — and publicly available — resources for engineering autotrophic and methanotrophic organisms (e.g., Clostridium, Methylocystis), as well as efforts to advance continuous gas bioreactor systems, are critical to enable the next generation of highly carbon negative chemicals.

  • Piyush Nanda

    Selection Phase Fermentation Strategy

    “The dream of every cell is to become two cells”
    -François Jacob

    Problem

    Mitigating climate change requires a rapid switch to biomanufacturing. Scalable biomanufacturing poses a dual challenge: i) effectively driving metabolic fluxes towards the formation of the product of interest (a metabolic engineering challenge) and ii) maintaining the engineered strains in their optimal bioproduction state during fermentation (a bioprocessing challenge). Natural selection complicates an engineer’s bioproduction objectives by favoring strains that grow faster throughout fermentation. Such growth dynamics lead to the enrichment of non-producing strains-fast dividing cheaters in the bioreactor, especially in a continuous reactor system (Rugbjerg et al. 2019, Nat. Biotech.). Addressing this challenge requires a new, innovative strategy.

    Several strategies are proposed, including deep DNA sequencing for actively monitoring the rise of such mutants. Moreover, recent studies have proposed coaxing strains towards bioproduction by driving an essential gene’s expression proportionately to the product generated – a strategy that will penalize non-producing strains (Rugbjerg et al. 2020). Despite years of research, we have yet to develop an easier-to-implement but scalable strategy. I propose a simple approach to counter-select fast-growing mutants by transiently changing from a ‘production mode’ to a ‘selection mode’.

    A risk-benefit tradeoff shapes growth rates. A cell can either allocate resources to reproduction-filling its cytosol with ribosomes and metabolic machinery to grow fast, or allocate a part of the resources towards accumulating proteins it might need during periods of starvation (Basan et al. 2020, Nature; Wu et al. 2022, PNAS). Studying the behavior of microbes in fluctuating environments has established tradeoffs between growth during feast and preparation for famine. Naturally occurring wild isolates of model yeast, Saccharomyces cerevisiae, show significant variations in the growth rate ( Chiara et al, 2022, Nat. Eco. and Evol.). Different strains were likely subjected to varying forms of environmental fluctuations. The presence of abundant glucose, like in a bioreactor, preferentially selects for populations with high growth rates. Meanwhile, periods of feasts followed by prolonged famines select strains that grow slowly but can survive well during famine.

    Solution

    I propose a new kind of fermentation strategy: Fluctuostat. This involves switching between a production phase (fermentation) and a selection phase (artificial famine induced by stressors). Fast-growing mutants will rise during the fermentation phase but will face a survival challenge during the selection phase, where slower-growing cell factories will get an evolutionary advantage. Of course, the selection phase won’t generate any bioproducts. Therefore, it is essential to estimate the duration of the selection phase so that effective productivity is maximized.

    Current studies (Rugbjerg et al. 2019, Nat. Biotech.; Figure 1) reveal a pressing issue: within just 60-70 generations of growth from a single colony to a 200 m3 bioreactor, a significant fraction, i.e. 40% of the population, is overtaken by non-producing strains-a substantial productivity cost to the industry. Determining which stressors will be best suited for the existing biomanufacturing infrastructure is crucial. This strategy presents an unexplored approach to improving productivity by subjecting a population of microbial cell factories to a fluctuating environment.

  • Kweku Opoku-Agyemang

    Modular Bioreactor Systems

    Concept
    Modular Bioreactor Systems for Scalable Synthetic Biology.

    The Problem
    Current fermentation systems are often designed for large-scale, single-product processes, which limits flexibility and adaptability. This one-size-fits-all approach hinders the scalability of synthetic biology applications that require customized conditions for different organisms and products.

    A Proposed Solution
    Develop a modular bioreactor system that can be easily reconfigured for different synthetic biology applications. Each module would be designed to cater to the specific needs of different organisms, allowing for optimal growth conditions and product yields. The system would include:

    Interchangeable Vessels: Different vessel designs that can be swapped out depending on the organism and product, ranging from micro-bioreactors for small-scale experiments to larger vessels for commercial production.
    Adaptive Control Systems: Smart control systems that can adjust parameters such as temperature, pH, and nutrient flow in real-time based on feedback from sensors monitoring the organisms’ growth and product formation.
    Scalable Architecture: A design that allows for the addition of more modules to increase production without the need for entirely new systems, thus reducing costs and increasing efficiency.
    Integrated Data Analysis: Software that can analyze data from the bioreactors to optimize conditions and predict outcomes, leading to faster iteration and improvement of synbio processes.

    This modular approach would allow manufacturers to scale their synthetic biology solutions more effectively, adapting quickly to new organisms and products without significant downtime or capital expenditure. It would also facilitate a more rapid transition from R&D to production, accelerating the path to market for new synbio innovations.

    Potential for Lifting All Boats:
    By providing a flexible and adaptable platform, this idea could serve a wide range of synthetic biology applications, from pharmaceuticals to biofuels, making it easier for the entire field to scale and meet the growing demand for sustainable and eco-friendly products.

    This concept aligns with Astera’s objectives by offering a tangible innovation that could be further explored in workshops and residencies, potentially attracting interest and investment from various stakeholders in the synthetic biology community.

  • Kenza Samlali

    Integrating Microcarriers

    Scaling mammalian cell culture for cell therapies is challenging for many reasons, including the cells’ preference for the physiological conditions of their natural environment, leading to low throughput and high costs. To address this, microcarriers—100-300 um beads—are becoming a popular solution to increase production capacity by enhancing the surface area of bioreactors. Similarly, in large scale fermentation of micro-organisms, solid state fermentation is an often used method. However, transitioning from screening into scaling still remains challenging as current high throughput screening methods are not capable of screening strains or cell lines for their ability to thrive in such environments. A proposed solution is to integrate microcarriers into screening steps using droplet microfluidics.

    TL;DR – Use microcarriers in screening steps early on, offering a means to increase yield and reduce strain failure during scaling from screening to large-scale fermentation.

  • Eye's Hand

    Open-Source Library of Cell Lines

    My general idea is to create an open-source library of cell lines with protein expression or other revolutionizing capabilities. The library could be a relatively modest collection of a specific cell type e.g. Chinese Hamster Ovary (CHO) cell lines, which are commonly used to produce therapeutic antibodies in the oncology / immunology space. In the case of CHO cell production, one of the industry bottlenecks is the use of antibiotics at large-scale. The over-use of antibiotics across the fields of human health, agriculture and livestock is of grave concern, with the potential to generate antibiotic-resistant pathogens. Therefore, the use of antibiotics in large-scale bioreactors is limited, if not prohibited. A library of metabolic knock-out (auxotrophic) CHO cell lines would allow selective growth of protein-producing cells by simple addition of the necessary metabolite to the growth media, with the advantage over today’s technology of complete elimination of the use of antibiotics in the process.

    On the other hand, the library of cell lines could be more extensive to include other mammalian cell types e.g. Human Embryonic Kidney (HEK) cells, which are often used for vaccine production among other industry uses. The library could go even further to include various metabolomic knock-out strains of Saccharomyces cerevisiae (baker’s yeast), which are much more amendable to genetic manipulation than the previously mentioned mammalian cell lines. Baker’s yeast could theoretically be engineered to metabolize environmental hazards (such as oil spills by utilizing petroleum as a carbon source) or produce an industrial product that is otherwise too costly or complex to make. The library could take one step further by incorporating various strains of (non-pathogenic) E. coli or other bacteria that are commonly used for protein production, with much quicker turnaround times due to their faster growth.

    Overall, I would love to see someone take this idea and run with it. Currently, the vast majority of CHO and other cell lines are only available through cost-prohibitive licensing / royalty agreements, such that only large corporations have access to the best protein-producing cells. Even then, production of the protein of interest is often linked to the use of antibiotics in the growth media, creating scale-up challenges as well as contributing to the environmental crisis that the global community is beginning to realize. Creation of an open-source library of metabolomic knock-out CHO cell lines would eliminate one bottleneck in the scale-up of therapeutic protein production that is currently used to treat patients who suffer from cancer and various immunological diseases.


In addition to our winning entries, we are delighted to showcase the diverse and creative ideas submitted by all our participants, which we believe have the potential to inspire further discussion, ideation, and iteration within the community. Consistent with the Call, we are reproducing all of these ideas in their entirety, save for a few that were off-topic. 

Thank you to everyone who contributed their vision and creativity to this initiative!