On March 27, 2025, the National Food Safety Standard — Procedures for Safety Assessment of Microorganisms Used in Food (GB 31615.2—2025) was officially released and will come into effect on March 16, 2026.
Compared with the draft for public comment, the final version refines and optimizes the requirements for bacterial pathogenicity and toxin production testing. It applies to live microbial strains used in food and food additives. As the core reference for strain registration and safety review, the publication of this standard will enhance the scientific rigor, regulatory consistency, and international alignment of food microorganism safety assessments.
CIRS Group has compared the changes between the final and draft versions and summarized the required experimental items for evaluating new food strains for the reference of enterprises.
Two key updates in the final version compared to the Draft for Public Comment
Compared to the 2023 draft for public comment, GB 31615.2—2025 introduces the following two substantial technical updates:
Clarification of experimental requirements for bacterial toxin production
In the 2023 draft, requirements regarding bacterial toxin production were not clearly defined, with a primary focus on fungal toxin production and detection methods. This caused confusion over whether bacteria should undergo toxin testing and how such experiments should be conducted.
The 2025 final version establishes a dedicated module for “Bacterial Toxin Production Testing”, explicitly requiring comprehensive genomic and expression analysis of toxin-related genes in bacterial strains. Through whole-genome sequencing, the presence of typical toxin-associated genes (such as hemolysins, enterotoxins, and exfoliative toxins) must be screened. Additionally, toxin (or antimicrobial substance) content (or activity) must be measured using multi-medium culturing and national standard detection methods. This addresses previous gaps in the standard and significantly strengthens the identification and control of potential bacterial toxicity risks.
Refinement of strain classification requirements in Appendix A: Bacterial Pathogenicity Testing Methods
In the 2023 draft, bacterial pathogenicity testing classified only the genera Bifidobacterium and Lactobacillus as major food-use bacteria, grouping all others under “Other Bacteria” without further distinctions among lactic acid bacteria.
The 2025 final version refines the classification of lactic acid bacteria, adding several genera—including Lacticaseibacillus, Limosilactobacillus, Lactiplantibacillus, Latilactobacillus, and Liquorilactobacillus—alongside Bifidobacterium and Lactobacillus as major food-use bacterial genera. All other bacterial strains remain categorized under Other Bacteria.
This adjustment improves the scientific basis and applicability of pathogenicity testing for lactic acid bacteria.
2. What experimental projects are required for the safety assessment of new strains?
According to the Procedures for Safety Assessment of Microorganisms Used in Food, a new strain typically needs to undergo the following experimental assessments:
- Strain Identification;
- Whole-Genome Sequencing;
- Antimicrobial Resistance Testing;
- Animal Pathogenicity Testing;
- Toxin Production Testing;
- Toxicological Testing; and
- Genetic Stability Analysis
Below, we provide a brief introduction to each experimental requirement for different types of microorganisms (bacteria, filamentous fungi, actinomycetes, and yeasts).
|
Item |
Objective |
Main Content Summary |
|
|
Strain Identification |
Phenotypic identification |
Confirm basic biological characteristics |
Conventional morphology, biochemical reactions, and staining. |
| Key homologous gene analysis |
Determine strain species information |
•Bacteria: 16S rRNA |
|
|
Whole-genome sequencing and analysis |
Determine the complete DNA sequence of the organism and analyze safety-related genetic features |
Perform whole-genome sequencing to obtain a draft and a complete genome map. Analyze sequencing data for virulence genes, antimicrobial resistance genes, and toxin-related genes. |
|
|
Genetic stability analysis |
Assess stability over subcultures |
Evaluate key indicators or traits of strains after more than twice the maximum number of subcultures within one production cycle, including traits, metabolites, key genes, and fermentation characteristics. |
|
|
Antimicrobial resistance testing |
Assess antibiotic resistance |
• Bacteria: Minimum Inhibitory Concentration (MIC) testing. |
|
|
Pathogenicity testing |
Assess strain pathogenicity (animal experiments) |
•Strains without history of use or with reports of adverse effects: intraperitoneal injection + oral gavage. |
|
|
Toxin production testing |
Verify toxin production by the strain |
•Bacteria: Based on whole-genome sequencing analysis, determine if testing is needed. |
|
|
Toxicological testing |
Verify strain toxicity |
For active strains without a history of consumption domestically or internationally, select appropriate toxicological tests based on the specific situation. |
|
Notes: For strains intended to be added directly to foods for infants under one year of age, D-lactic acid content must also be determined using testing methods specified in national food safety standards or other equivalent methods.
For strains exhibiting hemolytic activity or producing other metabolic substances, the presence of hemolytic substances or relevant metabolites must also be assessed using testing methods specified in national food safety standards or other equivalent methods.
Summary
The GB 31615.2–2025 National Food Safety Standard — Procedures for Safety Assessment of Microorganisms Used in Food provides a unified technical basis for the registration and regulatory oversight of food-use strains, ensuring their safety, stability, and regulatory compliance. While the standard does not apply to the safety assessment of genetically modified microorganisms (GMMs), it may still serve as a reference for certain safety evaluation experiments involving production strains used in the manufacture of food ingredients and food additives derived from GMMs.
About CIRS Food Division
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