Alzheimer’s disease (AD) urgently requires safe and effective early interventions. To address this unmet need, we developed Neurobloom, a probiotic capsule based on E. coli Nissle 1917, integrating three engineered systems.
Figure 1: Three system of our program
For this reason, we aim to leverage the power of synthetic biology to design a s
Figure 2：Alzheimer’s patients among the elderly.
In 2020, it was estimated that there were 727 million people aged 65 and above worldwide, accounting for 9.3% of the total population(Laskar, 2024). By 2050, this number is expected to more than double, exceeding 1.5 billion(Cohen, 2001). Many age-related diseases, such as diabetes, hypertension, and Alzheimer’s disease, are major contributors to mortality and disability among the elderly. This growing global aging trend poses significant challenges to families, public health systems, and the economy.
Figure 3：World population ageing （Cite from Urbanization Observation Network https://www.sohu.com/a/441941025_100291829）.
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder primarily characterized by a gradual decline in cognitive functions and memory loss. At the molecular level, AD is closely associated with the abnormal accumulation of amyloid-β (Aβ) plaques outside neurons and the hyperphosphorylation of tau protein inside neurons. These pathological changes disrupt normal neuronal function, impair synaptic communication, and ultimately lead to widespread neuronal death. Together, these processes result in cognitive deficits, memory impairment, and behavioral changes, which are hallmarks of the disease.
Figure 4: Cognitive deficits in Alzheimer’s disease are causally linked to synaptic loss. Synaptic dysfunction may arise from two pathological pathways: extracellular accumulation of amyloid-β (A) and intracellular aggregation of tau protein (B).(Cite from Mind the Graph).
With the intensifying global population aging, it has become a major public health challenge that seriously threatens the health and quality of life of the elderly. According to statistics, a new case of Alzheimer’s disease is diagnosed every three seconds worldwide and China has the highest number of AD patients in the world. Currently, there are approximately 10 million AD patients in China, and this number is expected to exceed 40 million by 2050(Zhang et al., 2024).
Figure 5: Alzheimer’s Disease.
The typical symptoms of Alzheimer’s disease are generally divided into three stages: early (mild), middle (moderate), and late (severe). In the early stage, patients usually retain insight into their condition and exhibit only mild symptoms, though family and friends may already notice abnormalities. During the middle stage, cognitive functions progressively decline, and patients increasingly require care and supervision. In the late stage, patients largely lose the ability to interact with the outside world and become fully dependent on others for daily living（Andrade et al., 2023; Scheltens et al., 2016）.
Figure 6：Symptoms of Alzheimer’s disease at different stages.
Current interventions for Alzheimer’s disease (AD) can be grouped into several approaches—drug therapy, non-drug therapy, targeted biologic therapy, and early diagnostic tools—each with significant limitations, including temporary symptom relief, individual variability, high cost, invasiveness, or difficulty of wide implementation, highlighting the urgent need for safe and effective early-stage interventions.
Figure 7: Comparison of Existing Therapeutic Approaches
A large number of patients are already in an irreversible stage by the time of diagnosis, missing the optimal window for intervention. This issue is particularly severe in low-income populations and developing regions, where medical resources are limited and screening coverage is low, making it even harder to implement new therapeutic approaches and exacerbating health inequities. By 2050, 70% of AD patients worldwide are expected to be concentrated in low-income regions, yet these areas account for less than 5% of global healthcare investment, and early diagnosis rates are below 10% (Tahami et al., 2022). Meanwhile, high-income countries account for 80% of AD drug development investment, leaving patients in low-income countries with limited access to novel therapies (Zhang et al., 2024).
Therefore, developing a safe, low-threshold, early-stage intervention health product for high-risk populations is not only an important strategy to delay the onset of AD but also a practical necessity to promote cognitive health equity on a global scale.
We genetically modified Escherichia coli to continuously synthesize sakuranetin and lysophosphatidylcholine (LPC) in vivo. Among them, sakuranetin has antioxidant effects and can inhibit Aβ deposition, whereas LPC can reduce the Aβ plaque burden in the brain and improve the structure of the gut microbiota by regulating the gut–brain axis. This model does not require frequent medication and enables sustained intervention—both reducing the adverse reactions of traditional drugs and overcoming the limitations of non-pharmacological approaches such as poor compliance and treatment interruption. We name this innovative intervention system --- Neurobloom.
The chassis microorganism we use is Escherichia coli Nissle 1917 (EcN), a probiotic strain derived from the human gut with a strong safety profile and well-established clinical applications. This strain was first isolated by Alfred Nissle in 1917 and has since been widely used in commercial probiotic products for the treatment of intestinal disorders, such as inflammatory bowel disease and irritable bowel syndrome (Lynch, 2022). EcN’s characteristics—such as the absence of endotoxins, a well-defined genetic background, and ease of cultivation—make it an ideal chassis microorganism for constructing “Neurobloom.”
Figure 8：E. coli Nissle 1917 (Cite from https://www.cdc.gov/ecoli/about/index.html).
Sakuranetin is a naturally occurring flavanone found in plants, with promising antioxidant and anti-inflammatory properties. Recent studies suggest that sakuranetin may exert neuroprotective effects by scavenging reactive oxygen species (ROS), inhibiting the release of pro-inflammatory mediators, and modulating neuroinflammatory responses(Junaid, 2023).
Figure 9: Structural formula of sakuranetin. Sakuranetin, also known as 5,4'-dihydroxy-7-methoxyflavanone, is an organic compound with the molecular formula C₁₆H₁₄O₅. It belongs to the flavanone class of compounds and represents the 7-methoxy derivative of naringenin.
In the field of neurodegenerative diseases—particularly Alzheimer’s disease (AD)—sakuranetin has shown potential therapeutic relevance. Its mechanisms of action may include the suppression of β-amyloid (Aβ)-induced neurotoxicity, attenuation of tau protein hyperphosphorylation and the associated cytoskeletal disruption, mitigation of neuroinflammation and oxidative stress, as well as the preservation of memory function and delay of cognitive decline(Li et al., 2019).
Figure 10：The function of sakuranetin.
Compared with traditional chemical synthesis, synthetic biology approaches offer a more sustainable strategy for sakuranetin production. By employing Escherichia coli as the host chassis and expressing flavonoid 7-O-methyltransferase (F7-OMT) to catalyze the conversion of (2S)-naringenin into (2S)-sakuranetin, this method achieves high catalytic efficiency under mild reaction conditions(Sun et al., 2022). It also presents significant potential for scalable and sustainable biomanufacturing.
In the initial design, an exogenous F7-OMT was introduced into Escherichia coli. Upon supplementation with naringenin, the engineered strain was able to autonomously synthesize sakuranetin.
Figure 11: Gene circuit design of the first-generation production system.
Since E. coli naturally contains S-adenosylmethionine (SAM), SAM is methylated with naringenin catalyzed by F7-OMT, thereby producing S-adenosylhomocysteine (SAH) and the target product, sakuranetin.
Figure 12: Conversion of naringenin to sakuranetin catalyzed by F7-OMT using SAM as the methyl donor.
The production of sakuranetin depends not only on the expression efficiency of F7-OMT but also heavily on the intracellular supply of SAM. Insufficient SAM can significantly limit the conversion efficiency. To address this, in the second-generation system design we introduced the
Two auxiliary modules were added:
Figure 13: Gene circuit design of the second-generation optimized production system.
When ATP is abundant, ydaO binds ATP and forms a transcription terminator structure, thereby suppressing downstream gene expression. Conversely, under low ATP conditions, ydaO remains in an open conformation, allowing transcription to proceed. Through this feedback mechanism, ydaO facilitates
Figure 14: Role of the ydaO riboswitch in dynamic ATP homeostasis control.
Building on the “SAM rebirth loop” of the second generation, our third-generation design made the cell use glucose more efficiently, channeling more raw materials toward SAM production. We also co-expressed cysE (serine acetyltransferase) to boost the supply of cysteine and methionine.
Figure 15: Gene circuit design of the third-generation optimized production system. ydaO operon from Bacillus subtilis (containing ydaO riboswitch, vhb, and ptxD)
As a result, the cell could maintain higher SAM levels, which provide sufficient methyl donors for F7-OMT and significantly increase sakuranetin yield.
Figure 16: Reaction schematic of the third-generation system, with the main enhancement highlighted in the dark-shaded box on the left(Sun et al., 2022).
Naringenin is a naturally occurring flavonoid abundantly found in citrus fruits. It possesses well-documented physiological activities, including antioxidant, anti-inflammatory, glucose-regulating, and lipid-lowering effects, and has broad application potential in the food and cosmetics industries.
Figure17: The structure of naringenin.
In our earlier design, sakuranetin production relied on external supplementation with naringenin. While this strategy is cost-effective and feasible for in vitro production of sakuranetin as a nutritional supplement, it poses limitations for practical use. Because sakuranetin synthesis entirely depends on continuous intake of naringenin, its effectiveness is highly vulnerable to patient compliance. Insights from our human practice activities in nursing homes revealed that many elderly individuals suffer from memory impairment and often fail to adhere to supplement intake regimens.
Figure 18: Inspiration for constructing an endogenous naringenin production system.
To address this limitation, we propose an in vivo production strategy based on the probiotic chassis E. coli Nissle 1917. By equipping this strain with a complete naringenin biosynthetic pathway, it can continuously produce sakuranetin directly in the gut, thereby improving patient compliance and therapeutic effectiveness.The naringenin biosynthetic pathway originates from L-tyrosine, which is first deaminated by tyrosine ammonia-lyase (TAL) to generate p-coumaric acid. 4-coumarate:CoA ligase (4CL) then converts this into p-coumaroyl-CoA, which undergoes condensation with three molecules of malonyl-CoA catalyzed by chalcone synthase (CHS) to form naringenin chalcone. Finally, chalcone isomerase (CHI) catalyzes the intramolecular cyclization of this intermediate, yielding naringenin—a bioactive flavonoid with established antioxidant and anti-inflammatory activities(Gomes et al., 2024).
Figure 19: Endogenous biosynthetic pathway for naringenin production.
According to the literature, the abundance of Bacteroides in the gut microbiota of AD mice is reduced, leading to a decrease in its metabolite lysophosphatidylcholine (LPC). Oral administration of Bacteroides ovatus to AD mice significantly reduced cerebral Aβ plaques and markedly improved synaptic function, cognitive performance, and neuroinflammation.
Figure 20: Microbiota - derived lysophosphatidylcholine alleviates Alzheimer's disease pathology via suppressing ferroptosis(Zha et al., 2025).
Studies have shown that LPC can reduce Aβ plaque deposition in the brain, restore synaptic function, alleviate cognitive impairment, attenuate glial cell activation, and inhibit demyelination, thereby slowing the progression of Alzheimer’s disease .
Figure 21：Chemical structure of lysophosphatidylcholine (LPC).
In System 2, we first introduced and expressed an exogenous PLA2 gene to enhance the strain’s capacity to metabolize phosphatidylcholine (PC) in the gut.
Figure 22: Gene circuit design of the LPC production system.
PLA2 catalyzes the hydrolysis of PC to generate LPC, a key metabolite that can enter systemic circulation and reach the brain. This design enables the continuous and efficient production of LPC, thereby maintaining a stable LPC concentration in serum, ultimately reducing cerebral Aβ deposition and delaying the progression of Alzheimer’s disease.
Figure 23: Reaction schematic of the LPC production system(System 2).
In synthetic biology applications, engineered bacteria are often designed as tools for drug production or delivery. However, they carry potential biosafety risks such as escape or unintended spread into the environment, necessitating strict safety measures. The suicide system (also known as a kill switch) is a commonly used strategy, with its core principle involving the introduction of lethal genes such as T4 holin and T4 lysozyme (collectively referred to as the T4 lysis system). Holin forms pores in the bacterial inner membrane, while lysozyme degrades the cell wall; together, they rapidly induce cell lysis and death(Couse, 1968). This system is highly efficient, irreversible, and has been widely applied in biosafety designs within synthetic biology. Building on this principle, we constructed a dual-layer suicide system combining a cold-inducible module for ex vivo containment and an arabinose-inducible module for in vivo clearance.
Figure 24: The introduction of T4 lysis.
The ex vivo suicide system is based on a cold-inducible switch (pCspA–T4 lysis). pCspA is the native promoter of the cold-shock protein in E. coli. Under intestinal conditions at 37 °C, pCspA remains inactive, allowing the engineered bacteria to survive and perform their metabolic functions. However, when the strain accidentally escapes into an external low-temperature environment (below 16 °C), pCspA is activated and drives the expression of T4 holin and T4 lysozyme. Their synergistic action rapidly lyses the cells, thereby effectively preventing unintended spread of the engineered bacteria into the natural environment.
Figure 25: Design principle of the cold-inducible suicide system.
The in vivo suicide system relies on the arabinose-inducible switch (pBAD–T4 lysis). Arabinose is a naturally occurring pentose that binds to the regulatory protein AraC and activates the pBAD promoter. When clearance of residual engineered bacteria in the gut is required, oral administration of arabinose can trigger this system, leading to high-level expression of T4 holin and T4 lysozyme. This induces self-lysis of the cells, thus enabling artificial and controllable elimination of the engineered bacteria.
Figure26: Design principle of the arabinose-inducible suicide system.
After describing the three systems individually, it is important to step back and view them as a unified journey inside the human body. Once a Neurobloom capsule is ingested, the engineered E. coli Nissle 1917 reaches the intestine and begins its work.
Inside the gut, the bacteria continuously produce
Finally, when intervention is no longer required, our dual-layer safety system comes into play. The
Figure 27: From ingestion to suicide: the full journey of neurobloom.
Figure 28: Application and implementation Flow
Currently, no medical therapy can truly reverse the symptoms of Alzheimer’s disease (AD). Existing drugs and interventions may alleviate certain manifestations or temporarily slow disease progression, but they cannot halt or cure AD. Given that AD develops over a very long preclinical and prodromal period, early intervention is more critical than late-stage treatment. Our product is therefore designed for high-risk groups—including individuals with a family history of AD, patients diagnosed with mild cognitive impairment (MCI), and older adults suffering from chronic conditions such as diabetes, hypertension, or hyperlipidemia (Moceri et al., 2000). In addition, people with a history of traumatic brain injury, long-term stress, or sleep disorders are also vulnerable. With aging, neurodegenerative changes become increasingly common, further raising susceptibility. By providing an evidence-based nutraceutical for early-stage intervention, our aim is to delay disease progression, improve quality of life, and reduce the long-term social and familial burden associated with AD (Szandruk et al., 2022).
To explore the potential real-world application of our engineered bacteria, we considered how large-scale production might be achieved. In our design, the engineered strain could be cultivated in bioreactors under biosafety-compliant conditions. By adjusting factors such as the carbon-to-nitrogen ratio, dissolved oxygen level, stirring rate, and pH, it would be possible to achieve high-density growth while maintaining bacterial activity. After cultivation, the cells could be harvested using centrifugation or membrane separation, followed by purification steps to remove residual medium. To facilitate long-term storage and transportation, we propose using freeze-drying under vacuum with protective agents, which helps preserve both viability and genetic stability. Notably, although our design includes a cold-inducible suicide module, the use of rapid lyophilization technology ensures that the bacteria enter dormancy before the expression of lytic proteins, thereby maintaining feasibility and biosafety during transportation. Finally, the lyophilized product would undergo quality testing and standardization to ensure safety and consistency.
This design thinking demonstrates not only the engineering feasibility of our project but also provides a foundation for its potential transition from laboratory research to real-world application.
When designing the final product form, we compared several options including beverages, tablets, and powders. Ultimately, we chose
Therefore, capsules combine stability, user compliance, and functional protection, making them the most appropriate choice for our project goals. This decision was also supported by feedback from domain experts and potential users (see Human Practices section).
Figure 29: Neurobloom capsule.
This product is formulated as a freeze-dried capsule, taken orally once daily. After entering the intestine, it enables the continuous release of sakuranetin and LPC, supporting early Alzheimer’s disease intervention and daily health maintenance. The design ensures ease of use and long-term stability.
Figure 30: Product manual
Figure 31: Product Advantages.
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