Implementation | CAU-China

Introduction

PhAgri is a phage-like particle system developed through synthetic biology to provide a safe, efficient, and sustainable solution for bacterial crop diseases. By integrating phage capsid production into engineered E. coli, it enables the genome-free packaging of toxin plasmids for precise bacterial elimination. This technology not only reduces pesticide residues and production costs but also promotes eco-friendly agriculture and lays the foundation for future applications in broader pathogen control and public health protection.

Although PhAgri is still in the stage of laboratory, we believe that it can play an important role in agriculture.

"The problems we address are those encountered by farmers in their production. Therefore, when conducting laboratory work, we must not only focus on the technology itself, but more importantly, put ourselves in farmers’ shoes to design products and promote their use," Professor Juan Liu, who specializes in rural development at the College of Economics and Management, China Agricultural University, told us. During her rural research, she has visited many villages and personally experienced the impact that yield losses caused by diseases can have on farmers.

Therefore, we actively engages with the global community, dedicated to thinking about how to truly bring our project to helping the world. We analyzed the feasibility of PhAgri to assess its future promotion and the potential support it may receive. Additionally, we designed product usage guide and manuals to fully explain PhAgri’s characteristics and application methods.

Feasibility Analysis

1.1 Technical Feasibility: Laboratory Verification and Technological Breakthrough

Mature Core Technology: The laboratory has completed the design and targeting verification of phage-like particles. It has integrated the T7 phage capsid production line into the E. coli MG1655 genome, enabling the IPTG-induced production of genome-free protein capsids. These capsids exclusively package rolling-circle plasmids containing the toxin gene MazF, which can efficiently kill target bacteria (e.g., Pseudomonas syringae).

1.2 Economic Feasibility: Cost Optimization and Revenue Assurance

1.2.1 Controllable Cost Structure

By designing small-scale fermenters, we have made it possible for farmers to produce (the pesticide) themselves. The raw materials for the pesticide are easily accessible, and leveraging Science and Technology Backyard helps reduce logistics and fixed asset costs. Overall, the unit cost is lower than that of imported biopesticides.

1.2.2 Clear Revenue Returns

On the one hand, the use of PhAgri can reduce losses caused by bacterial diseases in agricultural production; on the other hand, agricultural products with low pesticide residues are more likely to enter the market and fetch higher prices.

1.3 Social Feasibility: Demand Matching and Trust Building

1.3.1 Alignment with Farmers’ Needs

Surveys across multiple regions show that farmers’ core demands for new pesticides focus on reducing pesticide residues, increasing yields, and lowering costs. PhAgri fully meets these three needs - Farmers in Quzhou County, Hebei Province, have clearly stated their willingness to try safe and sustainable alternative technologies, while small-scale farmers in Africa have a strong demand for low-cost technologies.

1.3.2 A Sound Trust Mechanism

Relying on the “Science and Technology Backyard” model, graduate students and promoters are stationed in rural areas. They intuitively demonstrate the effectiveness through “field demonstrations + comparative experiments”; meanwhile, leveraging the characteristic of “acquaintance society”, leading farmers take the lead in trial use to create a demonstration effect and improve the trust rate.

1.3.3 High adaptability

This project adjusts the methods of technical guidance based on the knowledge levels of farmers in different regions. For instance, at the China-Africa Science and Technology Backyard, international students assist farmers in mastering spraying methods through a “theory - field - re-theory” mechanism, resulting in a high level of technical acceptance.

1.4 Policy Feasibility: Dual policy support at home and abroad

China is advancing the development of “Pilot Zone for Agricultural Green Development” and has clearly required that the proportion of biopesticide use be increased to 30% by 2025. As a new type of biopesticide, PhAgri can be included in local agricultural technology promotion catalogs and the scope of agricultural subsidies (for instance, Shandong Province has already included similar biopesticides in its green agricultural input procurement list). Meanwhile, internationally, the International Plant Protection Convention (IPPC) formulated by the FAO (Food and Agriculture Organization of the United Nations) encourages the application of biological control technologies, laying a foundation for the widespread promotion of PhAgri.

Usage and Promotion Guide

First, we plan to help vulnerable labor groups in the agricultural sector (such as left-behind women and elderly farmers) participate in the product production process through skills training and equipment support. The Science and Technology Backyards will uniformly provide safe and easy-to-use self-fermentation devices. Farmers only need to receive basic training to complete the preliminary preparation of products using fermentation materials that are easily accessible under rural conditions.

At the same time, the Science and Technology Backyards will conduct centralized supervision over the use of engineered bacteria to ensure that the entire process complies with biosafety requirements.

After completing the preliminary fermentation and preparation of the product, we have designed diversified application schemes tailored to different growth stages of crops, aiming to minimize yield losses caused by bacterial diseases:

Pre-sowing Stage: By directly applying the preparation to the soil and seeds, pathogenic bacteria latent in the soil can be effectively eliminated, reducing the infection risk at the source.

Growth Stage: When early disease symptoms (such as yellowing, spots, etc.) appear on crop leaves, spray the agent on the leaf surface to inhibit the spread of the disease.

To further improve the efficiency of agent application and environmental friendliness, we plan to develop a set of on-field precise detection and control systems. This system will integrate image recognition and model prediction technologies: it will first use drones to take photos of crop disease-affected areas for identification, and then calculate the number of pathogenic bacteria in these areas based on the characteristics of disease spots. Combined with the number of pathogenic bacteria, the minimum phage dose required to eliminate these pathogens can be determined using the minimum dose model we have constructed.

Subsequently, the system will calculate the minimum effective application amount based on the model prediction results and the general agent loss rate, thereby achieving precise agent application and optimal resource utilization, while reducing agent waste and environmental burden.

Of course, if no bacterial diseases occur in the region in a given year, the products produced can still be sold by companies through cooperation with the Science and Technology Backyards. (Many Science and Technology Backyards are established in parallel with companies, which helps improve the quality of agricultural products while standardizing sales.) This will also provide farmers with a considerable amount of income.

User Manual

Future Plans

We do not only aim to solve the problem of crop diseases caused by bacteria, but also strive to combat all bacteria that may pose a threat to human health.

Currently, it is not just these plant pathogens that affect human production and daily life: Salmonella and Klebsiella can cause severe intestinal problems; in the process of livestock and poultry production, large amounts of antibiotics are used to reduce bacterial infections, leading to antibiotic residues in meat; due to the abuse of antibiotics, there is a high possibility that “multidrug-resistant (MDR) bacteria” — which render all antibiotics ineffective — exist in our bodies… By means of tail fiber modification and toxin delivery, we hope to achieve targeted elimination of these pathogens, allowing PhAgri to become a guardian of human health. They can accurately identify pathogens and achieve in-situ elimination without affecting non-target organisms, thus making them the most promising pathogen elimination method.