The European Food Safety Authority (EFSA) has concluded that l-isoleucine produced by fermentation with the genetically modified strain Corynebacterium glutamicum CGMCC 32505 is safe for all animal species, consumers, and the environment when used as a nutritional feed additive, according to a scientific opinion adopted on 24 July 2026 and published on 10 August 2026. The opinion, issued by EFSA's Panel on Additives and Products or Substances used in Animal Feed (FEEDAP), also found the additive to be an effective source of the amino acid for non-ruminant species, though it noted that for ruminants it must be protected from ruminal degradation to be equally efficacious. The assessment follows a request from the European Commission under Regulation (EC) No 1831/2003, submitted by Xinjiang Fufeng Biotechnologies Co., Ltd., represented in the EU by Seres Biotech B.V., for authorisation of the additive for use in feed and water for drinking for all animal species.
The dossier was received by EFSA on 20 November 2025 and deemed valid on 27 February 2026. A public consultation on the non-confidential version of the technical dossier ran from 26 June 2026 to 17 July 2026, during which no comments were received, and a target consultation of interested Member States from 4 March 2026 to 4 June 2026 also yielded no comments. The production strain, deposited in the China General Microbiological Culture Collection Center with accession number 32505, is genetically modified to increase l-isoleucine production, but none of the modifications raised safety concerns. Viable cells or DNA of the production strain were not detected in the final product, and the strain was found susceptible to all relevant antibiotics with no acquired antimicrobial resistance genes. The additive is specified to contain at least 98.5% l-isoleucine on a dry matter basis, with a maximum moisture content of 2.0%.
The FEEDAP Panel expressed concerns about the use of amino acids in water for drinking, a recurring issue in its assessments of similar additives. Regarding user safety, the Panel could not conclude on the additive's potential to be irritant to skin and/or eyes or a skin sensitiser due to a lack of data. This opinion adds to a series of FEEDAP assessments on l-isoleucine produced by different fermentation strains, which are already authorised in the EU for all animal species as nutritional additives. The new opinion will inform the Commission's decision on whether to authorise this specific production strain, balancing the nutritional benefits for livestock producers against the need for comprehensive safety data, particularly for users handling the additive. The lack of data on irritancy and sensitisation could delay authorisation or prompt additional requirements, while the confirmed efficacy for non-ruminants supports its use in poultry and pig feed, potentially offering an alternative source of this essential amino acid.