The proposal, published in the journal Discover Biotechnology, builds on a growing body of work in plant-derived edible vaccines. The idea is deceptively simple: genetically engineer a plant to produce an antigen, a harmless fragment of a pathogen that the immune system can learn to recognize, and then have people or animals eat the plant tissue. When the antigen reaches the gut, it encounters the gut-associated lymphoid tissue, or GALT, a dense network of immune cells that guards one of the body’s main entry points for pathogens. Studies in both mice and humans have shown that plant-derived antigens delivered orally can stimulate antigen-specific mucosal IgA antibodies as well as serum IgG, the systemic antibody class measured after conventional immunization. That dual response matters, because mucosal immunity is the first line of defense against the respiratory and intestinal infections that cause enormous global disease burden.

Plant-based delivery also solves some stubborn engineering problems. The plant cell wall acts as a natural capsule, shielding antigenic proteins from the acidic environment of the stomach so they survive long enough to reach immune tissue. Even more striking, freeze-dried plant material expressing vaccine antigens has been shown to maintain antigen integrity at ambient temperatures, eliminating the need for refrigeration during storage and transport. For regions where electricity is unreliable and cold-chain logistics are prohibitively expensive, a vaccine that can sit on a shelf as dried powder is a fundamentally different proposition from one that must be kept chilled at every step.

Among the many plants tested as vaccine factories, duckweeds—tiny aquatic flowering plants of the family Lemnaceae—stand out. They pack protein at up to 40 percent of their dry weight, grow at remarkable speed on inexpensive byproduct substrates, and, crucially for vaccine consistency, are so small and anatomically uniform that antigen levels should be even between individual plants. That uniformity addresses one of the biggest weaknesses of edible vaccines in general: dosage. When a vaccine is eaten, the amount of antigen consumed can vary depending on which part of the plant is eaten and how much, leading to inconsistent immune responses. Researchers are countering this with genetic engineering strategies that drive uniform antigen expression in specific tissues, and duckweed’s near-homogeneous body plan gives it a natural head start.

The evidence in animal models is encouraging. Duckweed engineered to express Interleukin-17B has been used as a mucosal adjuvant against infectious bronchitis virus in chickens. When the M2e peptide of the H5N1 avian influenza virus—a sequence so conserved it appears across essentially all influenza strains—was expressed in duckweed and fed to mice, the animals produced anti-M2e antibodies detectable in blood serum. And in an aquaculture demonstration, zebrafish fed transgenic duckweed carrying the LamB antigen from Vibrio alginolyticus were protected against fish vibriosis: when challenged with five times the lethal dose of the pathogen, 63 percent of the vaccinated fish survived, compared with complete mortality in the unvaccinated control group.

So why has no one scaled this up? The answer lies in duckweed’s biology. Because the plants are aquatic, they need vast expanses of water to grow, and in water-scarce regions that requirement can outweigh the benefits of the vaccine itself. Artificial ponds would have to be built, consuming capital and competing with agriculture and urban development for land. Open-air ponds are also vulnerable to contamination by microalgae and fungi, which can render entire batches unusable and impose heavy financial losses. Finally, harvesting delicate, millimeter-scale plants is logistically awkward, and ponds are often located far from the end users, forcing complex delivery chains that erode the cost advantages that made duckweed attractive in the first place.

The research team’s answer is a vertical farming and recirculation system. Instead of spreading duckweed across horizontal ponds, the design stacks multiple layers of cultivation trays, with the liquid medium held at a shallow depth of roughly five centimeters—enough for duckweed, which floats at the surface, to thrive. Water is pumped to the top tray and flows gravitationally through the lower trays back to a reserve basin at the bottom, continuously recirculating and dramatically cutting water use. According to the authors, this vertical arrangement could raise production yield per unit area by a factor of ten to twenty compared with conventional cultivation. Biomass is collected with a filtration-based harvester that returns the supernatant to the basin, minimizing waste.

Vertical farms have a well-known Achilles’ heel: trays lower in the stack are shaded by those above. The proposed solution is elegantly mechanical. The trays would be made of transparent material and mounted on retractable mechanisms along both horizontal axes, with a programmable algorithm adjusting the retraction amplitude and frequency in response to real-time light sensors, so each layer of duckweed gets its optimal share of sunlight. Solar panels integrated into the structure would help offset the energy costs of pumping and automation. The team also proposes siting these systems on livestock and poultry farms, where animal wastewater could serve as the growth medium—turning a disposal problem into a nutrient source while the duckweed simultaneously purifies the water. Settling ponds can reduce turbidity and microbial load in the wastewater before use, and prior studies indicate that duckweed grown on wastewater does not suffer unsafe microbial contamination. Because the system is enclosed, it also limits environmental contamination and gene flow, aligning with global biosafety regulations; regular monitoring for heavy metals in the waste streams would be needed, with quality control applied across the value chain to meet Good Manufacturing Practice standards.

The envisioned value chain runs from molecular bioengineering to the dinner bowl. A gene encoding a pathogenic antigen is introduced into duckweed, the transformed plants are cultivated at scale in the retractable vertical trays, and the harvested biomass is dried and ground into a powder that can be mixed into food or feed—immunizing and nourishing the consumer at the same time. The capital costs of such a system, especially when fitted with solar panels, sensors, and automated retraction, exceed those of traditional greenhouse production, but they are far lower than bioreactor-based manufacturing, and operating expenses can be trimmed by optimizing light regimes. The authors argue that high yields and low downstream processing costs could give the approach a decisive edge in overall unit economics, with lighting costs and protein yield as the two variables that will ultimately determine competitiveness.

Significant hurdles remain before duckweed vaccines reach the main course. Purification steps are still required before the material can be used as a vaccine, and the regulatory pathway for an edible, plant-grown immunization is uncharted territory in most jurisdictions. Yet the convergence of advances in plant biotechnology—improved promoter optimization, enhanced expression systems, and synthetic biology tools—with a cultivation system designed for scale suggests that the gap between laboratory proof and global health impact may finally be closable. If powdered duckweed vaccines can be grown beside the farms and villages that need them, stored without refrigeration, and eaten rather than injected, one of medicine’s oldest tools could take on one of its most persistent inequities.

Subject of Research: Vertical farming of transgenic duckweed for scalable production of edible vaccines

Article Title: Vertical farming of duckweed: advancing edible vaccine production for global health

Article References: Grieš, M., Rosputinský, M., Mećava, M., & del Valle, A. C. (2025). Vertical farming of duckweed: advancing edible vaccine production for global health. Discover Biotechnology, 2(1), Article 14. https://doi.org/10.1007/s44340-025-00018-x

Image Credits: AI Generated

DOI: 10.1007/s44340-025-00018-x

Keywords: duckweed, edible vaccines, vertical farming, mucosal immunity, transgenic plants, Lemnaceae, cold chain, wastewater, antigen expression, global health, plant biotechnology, aquaculture