We report an ingestible, millimeter-sized microbial fuel cell (MFC) capsule that can provide a realistic and practical power solution for ingestible electronics. The capsule integrates a pH-sensitive enteric membrane, a germinant-containing layer, and a microfluidic hydrogel-based anodic channel pre-inoculated with Bacillus subtilis spores as dormant biocatalysts, which are directly connected to an integrated MFC. When the pH-sensitive membrane dissolves in a designated gut location with a specific pH, the hydrophilic hydrogel in the anodic channel absorb the gut fluids washing the germinant to trigger the spore germination and generate microbial metabolic electricity in our world’s smallest MFC. When the capsule is designed to work in the human intestine, it generates electricity only in the neutral pH solution achieving maximum power and current densities of 64μW/cm2 and 435 μA/cm2, respectively, which are substantially higher than the other energy harvesting techniques.
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Revolutionary self-powered transducing mechanism for long-lasting and stable glucose monitoring: achieving selective and sensitive bacterial endospore germination in microengineered paper-based platforms
We introduce a groundbreaking proof-of-concept for a novel glucose monitoring transducing mechanism, marking the first demonstration of a spore-forming microbial whole-cell sensing platform. The approach uses selective and sensitive germination of
- PAR ID:
- 10559863
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Microsystems & Nanoengineering
- Volume:
- 10
- Issue:
- 1
- ISSN:
- 2055-7434
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Transient electronics, which can operate only for short‐lived applications and then be eco‐friendly disintegrated, create opportunities in environmental sensing, healthcare, and hardware security. Paper‐based electronics, or papertronics, recently have rapidly advanced the physically transient device platform because paper as a foundation offers an environmentally sustainable and cost‐effective option for those increasingly pervasive and fast‐updated single‐use applications. Paper‐based power supplies are indispensable to realize a fully papertronic paradigm and are a critical enabler of environmentally benign power solutions. Microbial fuel cells (MFCs) hold great potential as power sources for such green papertronic applications. This work reports the design, operation, and optimization of a high‐power papertronic MFC by biosynthesizing microbe‐mediated tin oxide nanoparticles (SnO2NPs) on dormant Bacillus subtilis endospores. They form an electrical conduit that improves electron harvesting during the spore germination and power generation. The MFC is packaged in a sub‐microporous alginate to minimize the potential risk of bacteria leakage. Upon the introduction of water, the paper‐based MFC generates a significantly enhanced power density of 140 µW cm−2, which is more than two orders of magnitude greater than their previously reported counterparts. Six MFCs connected in series generate more than sufficient power to run an on‐chip, light‐emitting diode.
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Abstract Paenibacillus larvae, a Gram-positive bacterium, causes American foulbrood (AFB) in honey bee larvae (Apis mellifera Linnaeus [Hymenoptera: Apidae]). P. larvae spores exit dormancy in the gut of bee larvae, the germinated cells proliferate, and ultimately bacteremia kills the host. Hence, spore germination is a required step for establishing AFB disease. We previously found that P. larvae spores germinate in response to l-tyrosine plus uric acid in vitro. Additionally, we determined that indole and phenol blocked spore germination. In this work, we evaluated the antagonistic effect of 35 indole and phenol analogs and identified strong inhibitors of P. larvae spore germination in vitro. We further tested the most promising candidate, 5-chloroindole, and found that it significantly reduced bacterial proliferation. Finally, feeding artificial worker jelly containing anti-germination compounds to AFB-exposed larvae significantly decreased AFB infection in laboratory-reared honey bee larvae. Together, these results suggest that inhibitors of P. larvae spore germination could provide another method to control AFB.more » « less
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Although the evolution of spores was critical to the diversification of plants on land, sporogenesis is incompletely characterized for model plants such as Physcomitrium patens . In this study, the complete process of P. patens sporogenesis is detailed from capsule expansion to mature spore formation, with emphasis on the construction of the complex spore wall and proximal aperture. Both diploid (sporophytic) and haploid (spores) cells contribute to the development and maturation of spores. During capsule expansion, the diploid cells of the capsule, including spore mother cells (SMCs), inner capsule wall layer (spore sac), and columella, contribute a locular fibrillar matrix that contains the machinery and nutrients for spore ontogeny. Nascent spores are enclosed in a second matrix that is surrounded by a thin SMC wall and suspended in the locular material. As they expand and separate, a band of exine is produced external to a thin foundation layer of tripartite lamellae. Dense globules assemble evenly throughout the locule, and these are incorporated progressively onto the spore surface to form the perine external to the exine. On the distal spore surface, the intine forms internally, while the spiny perine ornamentation is assembled. The exine is at least partially extrasporal in origin, while the perine is derived exclusively from outside the spore. Across the proximal surface of the polar spores, an aperture begins formation at the onset of spore development and consists of an expanded intine, an annulus, and a central pad with radiating fibers. This complex aperture is elastic and enables the proximal spore surface to cycle between being compressed (concave) and expanded (rounded). In addition to providing a site for water intake and germination, the elastic aperture is likely involved in desiccation tolerance. Based on the current phylogenies, the ancestral plant spore contained an aperture, exine, intine, and perine. The reductive evolution of liverwort and hornwort spores entailed the loss of perine in both groups and the aperture in liverworts. This research serves as the foundation for comparisons with other plant groups and for future studies of the developmental genetics and evolution of spores across plants.more » « less
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