bims-livmat 2025-05-18 papers

ACS Biomater Sci Eng. 2025 May 13.

Adaptations of Gram-Negative and Gram-Positive Probiotic Bacteria in Engineered Living Materials.

Varun Sai Tadimarri, Tanya Amit Tyagi, Cao Nguyen Duong, Sari Rasheed, Rolf Müller, Shrikrishnan Sankaran.

Encapsulation of microbes in natural or synthetic matrices is a key aspect of engineered living materials, although the influence of such confinement on microbial behavior is poorly understood. A few recent studies have shown that the spatial confinement and mechanical properties of the encapsulating material significantly influence microbial behavior, including growth, metabolism, and gene expression. However, comparative studies within different bacterial species under identical confinement conditions are limited. In this study, Gram-negative Escherichia coli Nissle 1917 and Gram-positive Lactiplantibacillus plantarum WCFS1 were encapsulated in hydrogel matrices, and their growth, metabolic activity, and recombinant gene expression were examined under varying degrees of hydrogel stiffness, achieved by adjusting the polymer concentration and chemical cross-linking. Both bacteria grow from single cells into confined colonies, but more interestingly, in E. coli gels, mechanical properties influenced colony growth, size, and morphology, whereas this did not occur in L. plantarum gels. However, with both bacteria, increased matrix stiffness led to higher levels of recombinant protein production within the colonies. By measuring metabolic heat from the bacterial gels using the isothermal microcalorimetry technique, it was inferred that E. coli adapts to the mechanical restrictions through multiple metabolic transitions and is significantly affected by the different hydrogel properties. Contrastingly, both of these aspects were not observed with L. plantarum. These results revealed that despite both bacteria being gut-adapted probiotics with similar geometries, mechanical confinement affects them considerably differently. The weaker influence of matrix stiffness on L. plantarum is attributed to its slower growth and thicker cell wall, possibly enabling the generation of higher turgor pressures to overcome restrictive forces under confinement. By providing fundamental insights into the interplay between mechanical forces and bacterial physiology, this work advances our understanding of how matrix properties shape bacterial behavior. The implications of these findings will aid the design of engineered living materials for therapeutic applications.

Keywords: bacterial physiology; engineered living materials; microbial behavior; spatial confinement

DOI: https://doi.org/10.1021/acsbiomaterials.5c00325

ACS Appl Mater Interfaces. 2025 May 15.

Engineered Probiotics-Based Biohybrid-Driven Tumor Metabolic Remodeling To Boost Tumor Photoimmunotherapy.

Qinglian Hu, Xiaoyu Huang, Tong Wang, Zhuoting Lu, Dongchang Sun, Yuanxiang Jin.

Bioengineered probiotics enable new opportunities to address abnormal cancer metabolism and suppressive immune-environment interactions for improved therapeutic susceptibility. Here, Escherichia coli Nissle 1917 (EcN) was constructed to convert ammonia into l-arginine continuously and was further modified with polydopamine (PDA) to form living biotherapeutic argEcN@P for enhanced colorectal cancer eradication. Benefiting from the movement of EcN, argEcN@P could colonize and penetrate deep in tumors through hypoxia targeting and increase the intratumoral l-arginine concentrations. Upon near-infrared light (NIR) irradiation, heating induced by PDA could ablate tumor cells efficiently and release tumor antigens, which induce immunogenic cell death (ICD). More interestingly, argEcN@P remarkably promotes differentiation into M1-like macrophages in tumor tissues, inhibiting primary, distant tumor growth by inducing potent adaptive antitumor immunity. More importantly, argEcN@P treatment efficiently prevented postoperative tumor recurrence by inducing long-term immune memory. Taken together, this platform based on bioengineered probiotics provides a promising strategy for tumor metabolic reprogramming sensitized photothermal immunotherapy in deep tumors.

Keywords: engineered probiotics; metabolic reprogramming; photoimmunotherapy; polydopamine; synthetic biology

DOI: https://doi.org/10.1021/acsami.5c02850

ACS Synth Biol. 2025 May 16.

Design of a Continuous GAA-Producing Probiotic as a Potential Mitigator of the Effects of Sleep Deprivation.

Brandon D Fields, Daniel G Pascal, Olivia K Rando, Mary E Huddleston, Katherine Ingram, Rachel Hopton, Matthew W Grogg, M Tyler Nelson, Christopher A Voigt.

Creatine is a popular athletic supplement that has also been shown to improve cognitive performance upon sleep deprivation. However, it is rapidly cleared from the gastrointestinal tract a few hours after consumption. Toward providing a persistent creatine dose, we engineered the human probiotic Escherichia coli Nissle (EcN) to produce guanidinoacetic acid (GAA), which is converted to creatine in the liver. We find GAA-producing enzymes present in the human microbiome and compare their activities to known enzymes. Three copies of arginine:glycine amidinotransferase (AGAT) from Actinokineospora terrae are expressed from the genome, and native gcvP, argR, and argA are edited or deleted to improve substrate availability without negatively impacting cell viability. A standard EcN dose (1012 cells) produces 41 ± 7 mg GAA per hour under laboratory conditions. This work demonstrates that a probiotic bacterium can be engineered to produce sustained GAA titers known to impact cognitive performance.

Keywords: human performance enhancement; living therapeutic; synthetic biology

DOI: https://doi.org/10.1021/acssynbio.4c00690

BMC Biotechnol. 2025 May 13. 25(1): 36

Metabolic engineering for microbial production of sugar acids.

Fatma Gizem Avci, Tim Prasun, Volker F Wendisch.

Carbohydrates including sugar acids are commonly used as carbon sources in microbial biotechnology. These sugar acids are themselves desirable and often overlooked targets for biobased production since they find applications in a broad range of industries, examples include food, construction, medical, textile, and polymer industries. Different stages of oxidation for natural sugar acids can be distinguished. Oxidation of the aldehyde group yields aldonic acids, oxidation of the primary hydroxy group leads to uronic acids, and both oxidations combined yield aldaric acids. While the chemical oxidation of sugars to their acid forms often is a one-pot reaction under harsh conditions, their biosynthesis is much more delicate. Bio-based production can involve enzymatic conversion, whole-cell biotransformation, and fermentation. Generally, the in vivo approaches are preferred because they are less resource-intensive than enzymatic conversion. Metabolic engineering plays a crucial role in optimizing microbial strains for efficient sugar acid production. Strategies include pathway engineering to overexpress key enzymes involved in sugar oxidation, deletion of competing pathways to enhance the precursor availability and eliminate the product consumption, cofactor balancing for efficient redox reactions, and transporter engineering to facilitate precursor import or sugar acid export. Synthetic biology tools, such as CRISPR-Cas and dynamic regulatory circuits, have further improved strain development by enabling precise genetic modifications and adaptive control of metabolic fluxes. The usage of plant biomass hydrolysates for bio-based production further adds to the environmental friendliness of the in vivo approaches. This review highlights the different approaches for the production of C5 and C6 sugar acids, their applications, and their catabolism in microbes.

Keywords: Biocatalysis; Bioconversion; Fermentation; Metabolic engineering; Microorganism; Sugar acids

DOI: https://doi.org/10.1186/s12896-025-00973-7