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Engineered living materials (ELMs) are an emerging class of materials that are synthesized and/or populated by living cells to achieve novel functionalities including self‐healing and sensing. Providing nutrients to living cells within an ELM over prolonged periods remains a major technical challenge that limits the service life of ELMs. Bone maintains living cells for decades by delivering nutrients through a network of nanoscale channels punctuated by microscale pores. Nutrient transfer in bone is enabled by mechanical loading experienced by the material during regular use. Herein, the geometric traits of the network of channels and pores that can be used in ELMs to allow mechanical loading to enable nutrient delivery to resident cell populations are identified in a manner seen in bone. Transport occurs when deformation in the microscale pore network exceeds the volume of the connecting channels. Computational models show that transport is enhanced at greater loading magnitudes and lower loading frequencies. The computational results are confirmed using experiments with microfluidic systems. In the findings, quantitative design principles are provided for channel‐pore networks capable of sustained delivery of nutrients to living cells within materials.
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Engineering Bacillus subtilis for the formation of a durable living biocomposite material
Abstract Engineered living materials (ELMs) are a fast-growing area of research that combine approaches in synthetic biology and material science. Here, we engineer B. subtilis to become a living component of a silica material composed of self-assembling protein scaffolds for functionalization and cross-linking of cells. B. subtilis is engineered to display SpyTags on polar flagella for cell attachment to SpyCatcher modified secreted scaffolds. We engineer endospore limited B. subtilis cells to become a structural component of the material with spores for long-term storage of genetic programming. Silica biomineralization peptides are screened and scaffolds designed for silica polymerization to fabricate biocomposite materials with enhanced mechanical properties. We show that the resulting ELM can be regenerated from a piece of cell containing silica material and that new functions can be incorporated by co-cultivation of engineered B. subtilis strains. We believe that this work will serve as a framework for the future design of resilient ELMs.
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- Award ID(s):
- 2011401
- PAR ID:
- 10324202
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Engineered living materials (ELMs) have broad applications for enabling on‐demand bioproduction of compounds ranging from small molecules to large proteins. However, most formulations and reports lack the capacity for storage beyond a few months. In this study, we develop an optimized procedure to maximize stress resilience of yeast‐laden ELMs through the use of desiccant storage and 10% trehalose incubation before lyophilization. This approach led to over 1‐year room temperature storage stability across a range of strain genotypes. In particular, we highlight the superiority of exogenously added trehalose over endogenous, engineered production in yielding robust preservation resilience that is independent of cell state. This simple, effective protocol enables sufficient accumulation of intracellular trehalose over a short period of contact time across a range of strain backgrounds without requiring the overexpression of a trehalose importer. A variety of microscopic analysis including µ‐CT and confocal microscopy indicate that cells form spherical colonies within F127‐BUM ELMs that have variable viability upon storage. The robustness of the overall procedure developed here highlights the potential for widespread deployment to enable on‐demand, cold‐chain independent bioproduction.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1038/s41467-021-27467-2
