Evaluate antimicrobial compound production to support regulatory safety assessment of microbial strains.
Antimicrobial activity testing evaluates whether a microbial strain produces compounds that inhibit the growth of other microorganisms. This is a key component of microbial safety assessment, as antimicrobial metabolites may impact microbiota or contribute to the spread of antimicrobial resistance. BaseClear provides standardized antimicrobial activity testing using culture supernatants or final products to detect biologically active compounds.
This service is intended for companies developing microbial products for food, feed, enzymes, or biotechnology applications where regulatory approval is required.
Antimicrobial activity is assessed using an agar diffusion method under optimized and validated conditions to ensure robust and reproducible results. Findings are interpreted in the context of genomic data and antimicrobial resistance profiles to evaluate their regulatory relevance.
Clients receive a comprehensive report including experimental design, test conditions, results of activity assays, and regulatory interpretation. The report clearly states whether antimicrobial activity is detected and assesses its potential relevance for safety. Results are structured to support inclusion in regulatory dossiers as part of a weight-of-evidence safety assessment.
We define the testing scope, including selection of sample type (culture supernatant or product), indicator strains, and assay conditions based on regulatory requirements.
Samples are prepared under controlled conditions to reflect production processes, including collection of culture supernatants or preparation of final products for testing.
Antimicrobial activity is evaluated using validated assays against indicator strains recommended by EFSA.
Results are interpreted in a regulatory context, considering relevance, exposure, and supporting data, and delivered in a structured, dossier-ready report.
Functional testing integrated with genomic analysis for comprehensive risk interpretation
Designed to meet EFSA and international regulatory requirements
Tailored assay design based on strain, product, and regulatory requirements
Indicator strains selected to maximise relevance and detection sensitivity
Antimicrobial activity testing is required to identify whether a production strain produces compounds that inhibit other microorganisms. Such activity may affect microbiota or indicate the presence of bioactive metabolites that need to be evaluated for safety.
Sample selection for antimicrobial activity testing follows EFSA guidance and depends on the intended use of the microorganism. For active agents, the culture supernatant of the strain should be tested. For production strains or biomass-producing organisms, both the culture supernatant and/or the fermentation product should be evaluated. Samples should preferentially be obtained from the industrial-scale process, with the exact manufacturing stage specified. Where industrial material is unavailable, pilot-scale samples may be used, provided it is demonstrated that the process is representative of industrial production.
Indicator strains are selected to represent a range of Gram-positive and Gram-negative bacteria with known susceptibility to different antimicrobial classes. According to EFSA recommendations, a panel of at least six reference strains should be included, such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, Bacillus spp., and Streptococcus pyogenes. Results are reported individually for each indicator strain to support regulatory evaluation.
Detection of antimicrobial activity requires further investigation but does not automatically indicate a safety concern. EFSA guidance states that the nature of the activity must be characterised to exclude the production of therapeutic antimicrobials. When relevant biosynthetic genes are identified, quantitative analysis of culture supernatants or final products is required, including assessment of sub-inhibitory concentrations. If no genes and no activity are detected, the strain is considered not to produce relevant antimicrobials. In all other cases, a case-by-case assessment is required.
Antimicrobial activity testing may require follow-up studies depending on the observed results. If significant activity is detected, additional investigations such as compound identification, quantification, or toxicological testing may be needed to assess relevance for safety under intended use conditions.
Contact our experts to design a compliant and reliable testing strategy. Your first consultation is free and without obligation
