3D extrusion bioprinting of microbial inks for biomedical applications.

In recent years, the field of 3D bioprinting has witnessed the intriguing development of a new type of bioink known as microbial inks. Bioinks, typically associated with mammalian cells, have been reimagined to involve microbes, enabling many new applications beyond tissue engineering and regenerative medicine. This review presents the latest advancements in microbial inks, including their definition, types, composition, salient characteristics, and biomedical applications.

Mechanically Tunable, Compostable, Healable and Scalable Engineered Living Materials.

Advanced design strategies are essential to realize the full potential of engineered living materials, including their biodegradability, manufacturability, sustainability, and ability to tailor functional properties. Toward these goals, we present mechanically engineered living material with compostability, healability, and scalability - a material that integrates these features in the form of a stretchable plastic that is simultaneously flushable, compostable, and exhibits the characteristics of paper. This plastic/paper-like material is produced in scalable quantities (0.

Programmable microbial ink for 3D printing of living materials produced from genetically engineered protein nanofibers.

Living cells have the capability to synthesize molecular components and precisely assemble them from the nanoscale to build macroscopic living functional architectures under ambient conditions. The emerging field of living materials has leveraged microbial engineering to produce materials for various applications but building 3D structures in arbitrary patterns and shapes has been a major challenge. Here we set out to develop a bioink, termed as "microbial ink" that is produced entirely from genetically engineered microbial cells, programmed to perform a bottom-up, hierarchical self-assembly of protein monomers into nanofibers, and further into nanofiber networks that comprise extrudable hydrogels.

Robust Self-Regeneratable Stiff Living Materials Fabricated from Microbial Cells.

Living systems have not only the exemplary capability to fabricate materials (. wood, bone) under ambient conditions but they also consist of living cells that imbue them with properties like growth and self-regeneration. Like a seed that can grow into a sturdy living wood, we wondered: can living cells alone serve as the primary building block to fabricate stiff materials? Here we report the fabrication of stiff living materials (SLMs) produced entirely from microbial cells, without the incorporation of any structural biopolymers (.

Water-processable, biodegradable and coatable aquaplastic from engineered biofilms.

Petrochemical-based plastics have not only contaminated all parts of the globe, but are also causing potentially irreversible damage to our ecosystem because of their non-biodegradability. As bioplastics are limited in number, there is an urgent need to design and develop more biodegradable alternatives to mitigate the plastic menace. In this regard, we report aquaplastic, a new class of microbial biofilm-based biodegradable bioplastic that is water-processable, robust, templatable and coatable.

Engineered E. coli Nissle 1917 for the delivery of matrix-tethered therapeutic domains to the gut.

Mucosal healing plays a critical role in combatting the effects of inflammatory bowel disease, fistulae and ulcers. While most treatments for such diseases focus on systemically delivered anti-inflammatory drugs, often leading to detrimental side effects, mucosal healing agents that target the gut epithelium are underexplored. We genetically engineer Escherichia coli Nissle 1917 (EcN) to create fibrous matrices that promote gut epithelial integrity in situ.

Genetically Programmable Self-Regenerating Bacterial Hydrogels.

A notable challenge for the design of engineered living materials (ELMs) is programming a cellular system to assimilate resources from its surroundings and convert them into macroscopic materials with specific functions. Here, an ELM that uses Escherichia coli as its cellular chassis and engineered curli nanofibers as its extracellular matrix component is demonstrated. Cell-laden hydrogels are created by concentrating curli-producing cultures.

Biomimetic engineering of conductive curli protein films.

Bioelectronic systems derived from peptides and proteins are of particular interest for fabricating novel flexible, biocompatible and bioactive devices. These synthetic or recombinant systems designed for mediating electron transport often mimic the proteinaceous appendages of naturally occurring electroactive bacteria. Drawing inspiration from such conductive proteins with a high content of aromatic residues, we have engineered a fibrous protein scaffold, curli fibers produced by Escherichia coli bacteria, to enable long-range electron transport.

Fabrication of Amyloid Curli Fibers-Alginate Nanocomposite Hydrogels with Enhanced Stiffness.

Alginate hydrogels are biocompatible, biodegradable, low-cost, and widely used as bioinks, cell encapsulates, three-dimensional culture matrices, drug delivery systems, and scaffolds for tissue engineering. Nevertheless, their limited stiffness hinders their use for certain biomedical applications. Many research groups have tried to address this problem by reinforcing alginate hydrogels with graphene, carbon nanotubes, or silver nanoparticles.

Modulating bacterial and gut mucosal interactions with engineered biofilm matrix proteins.

Extracellular appendages play a significant role in mediating communication between bacteria and their host. Curli fibers are a class of bacterial fimbria that is highly amenable to engineering. We demonstrate the use of engineered curli fibers to rationally program interactions between bacteria and components of the mucosal epithelium.

Engineered Living Materials: Prospects and Challenges for Using Biological Systems to Direct the Assembly of Smart Materials.

Vast potential exists for the development of novel, engineered platforms that manipulate biology for the production of programmed advanced materials. Such systems would possess the autonomous, adaptive, and self-healing characteristics of living organisms, but would be engineered with the goal of assembling bulk materials with designer physicochemical or mechanical properties, across multiple length scales. Early efforts toward such engineered living materials (ELMs) are reviewed here, with an emphasis on engineered bacterial systems, living composite materials which integrate inorganic components, successful examples of large-scale implementation, and production methods.

Scalable Production of Genetically Engineered Nanofibrous Macroscopic Materials via Filtration.

As interest in using proteins to assemble functional, biocompatible, and environmentally friendly materials is growing, developing scalable protocols for producing recombinant proteins with customized functions coupled to straightforward fabrication processes is becoming crucial. Here, we use bacteria to produce amyloid protein nanofibers that are key constituents of the biofilm extracellular matrix and show that protein nanofiber aggregates can be purified using a fast and easily accessible vacuum filtration procedure. With their extreme resistance to heat, detergents, solvents, and denaturing agents, engineered curli nanofibers remain functional throughout the rigorous processing and can be used to assemble macroscopic materials directly from broth culture.

The role of residue C410 on activation of the human vitamin D receptor by various ligands.

Nuclear receptors (NRs) are ligand-activated transcription factors that regulate the expression of genes involved in biologically important processes. The human vitamin D receptor (hVDR) is a member of the NR superfamily and is responsible for maintaining calcium and phosphate homeostasis. This receptor is activated by its natural ligand, 1α, 25-dihydroxyvitamin D(3) (1α, 25(OH)(2)D(3)), as well as bile acids such as lithocholic acid (LCA).

A human vitamin D receptor mutant activated by cholecalciferol.

The human vitamin D receptor (hVDR) is a member of the nuclear receptor superfamily, involved in calcium and phosphate homeostasis; hence implicated in a number of diseases, such as Rickets and Osteoporosis. This receptor binds 1α,25-dihydroxyvitamin D(3) (also referred to as 1,25(OH)(2)D(3)) and other known ligands, such as lithocholic acid. Specific interactions between the receptor and ligand are crucial for the function and activation of this receptor, as implied by the single point mutation, H305Q, causing symptoms of Type II Rickets.

Identification, cloning, expression, and characterization of a highly thermostable single-stranded-DNA-binding protein (SSB) from Deinococcus murrayi.

We report identification and characterization of SSB-like protein from Deinococcus murrayi (DmuSSB). PCR-derived DNA fragment containing the complete structural gene for DmuSSB was cloned and expressed in Escherichia coli. The gene consisted of an open reading frame of 826 nucleotides encoding a protein of 276 amino acid residues with a calculated molecular weight of 30.

Novel thermostable single-stranded DNA-binding protein (SSB) from Deinococcus geothermalis.

To study the biochemical properties of single-stranded DNA-binding (SSB) protein from Deinococcus geothermalis (DgeSSB), we have cloned the ssb gene obtained by PCR and developed an overexpression system. The gene consists of an open reading frame of 900 nucleotides encoding a protein of 300 amino acids with a calculated molecular weight of 32.45 kDa.