L-isoleucine from Escherichia coli CCTCC M 20231916 in feed and water for drinking: IEC-VIS/FLD, endotoxins according to Ph. Eur. 2.6.14, specific optical rotation +36.25° below the pharmacopoeia range with 5.9 % valine
Commission Implementing Regulation (EU) 2026/1117, published on 27 May 2026, authorises until 16 June 2036 L-isoleucine (at least 90 % on a dry matter basis) produced by a genetically modified E. coli K12 derivative, CCTCC M 20231916, for all animal species, also in water for drinking despite EFSA’s concerns about hygiene and nutritional balance. User exposure to endotoxins is limited to 1 600 IU/m³ of air.
- Methods: identification according to the Food Chemicals Codex monograph; determination in the additive — ion-exchange chromatography with post-column derivatisation and optical detection (IEC-VIS/FLD or IEC-VIS), in premixtures IEC-VIS/FLD or IEC-VIS according to Regulation (EC) No 152/2009, in compound feed IEC-VIS (152/2009), in water for drinking IEC-VIS. Endotoxins — European Pharmacopoeia 2.6.14; exposure is calculated from endotoxin content and dusting potential by the EFSA method (EFSA Journal 2018;16(10):5458). Moisture is stated on the label.
- EFSA data (5 batches): isoleucine 91.0–92.2 % DM (method stated as EN ISO 17180:2013), valine 5.3–6.3 %, loss on drying 0–0.1 %; specific optical rotation +36.25° against the Ph. Eur. range of +40.0 to +43.0° — the applicant attributes this to other amino acids (on average 5.9 % L-valine). On average 97.5 % of the material on a DM basis was identified. Neither viable cells nor DNA of the strain were detected (DNA limit of detection 0.1 ng/g).
- Impurities (3 batches): lead 0.029–0.035 mg/kg, PCDD/F 0.121 and PCDD/F + PCB 0.237 ng WHO-TEQ/kg (upper bound), endotoxins < 30 IU/mg; dusting potential 36.3–37.9 g/m³. Losses: in a vitamin–mineral premixture 2.6–16.0 % after 6 months, on pelleting (72–73 °C) 0–8 %, in water 0–5.0 % after 48 h at 8–10 °C; coefficient of variation in pelleted feed 4 % for total and 26 % for free isoleucine.
- EFSA: the additive is safe for animals when supplemented according to their needs, with concerns about water for drinking; in ruminants protection against rumen degradation is required. There were no data on skin and eye irritation or skin sensitisation; given the dusting potential EFSA considered inhalation likely and advised minimising endotoxin exposure, citing the Dutch recommended limit of 90 IU/m³ (8-hour average). The label must remind users of the supply of all essential amino acids when given in water.