Protein‐based biomaterials have played a key role in tissue engineering, and additional exciting applications as self‐healing materials and sustainable polymers are emerging. Over the past few decades, recombinant expression and production of various fibrous proteins from microbes have been demonstrated; however, the resulting proteins typically must then be purified and processed by humans to form usable fibers and materials. Here, we show that the Gram‐positive bacterium
Silk proteins have emerged as versatile biomaterials with unique chemical and physical properties, making them appealing for various applications. Among them, spider silk, known for its exceptional mechanical strength, has attracted considerable attention. Recombinant production of spider silk represents the most promising route towards its scaled production; however, challenges persist within the upstream optimization of host organisms, including toxicity and low yields. The high cost of downstream cell lysis and protein purification is an additional barrier preventing the widespread production and use of spider silk proteins. Gram-positive bacteria represent an attractive, but underexplored, microbial chassis that may enable a reduction in the cost and difficulty of recombinant silk production through attributes that include, superior secretory capabilities, frequent GRAS status, and previously established use in industry.
In this study, we explore the potential of gram-positive hosts by engineering the first production and secretion of recombinant spider silk in the
It is hypothesized that the supplementation strategy addressed metabolic bottlenecks, specifically depletion of ATP and NADPH within the central metabolism, that were previously observed for an
- NSF-PAR ID:
- 10487764
- Publisher / Repository:
- Springer Science + Business Media
- Date Published:
- Journal Name:
- Microbial Cell Factories
- Volume:
- 23
- Issue:
- 1
- ISSN:
- 1475-2859
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Protein‐based biomaterials have played a key role in tissue engineering, and additional exciting applications as self‐healing materials and sustainable polymers are emerging. Over the past few decades, recombinant expression and production of various fibrous proteins from microbes have been demonstrated; however, the resulting proteins typically must then be purified and processed by humans to form usable fibers and materials. Here, we show that the Gram‐positive bacterium
Bacillus subtilis can be programmed to secrete silk through its translocon via an orthogonal signal peptide/peptidase pair. Surprisingly, we discover that this translocation mechanism drives the silk proteins to assemble into fibers spontaneously on the cell surface, in a process we call secretion‐catalyzed assembly (SCA). Secreted silk fibers form self‐healing hydrogels with minimal processing. Alternatively, the fibers retained on the membrane provide a facile route to create engineered living materials fromBacillus cells. This work provides a blueprint to achieve autonomous assembly of protein biomaterials in useful morphologies directly from microbial factories. -
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Results Herein, we report the development of a new strain of
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