L-tryptophan from Escherichia coli CCTCC M 2024517: HPLC-FLD according to EN ISO 13904, EBT impurity up to 10 mg/kg, unprotected tryptophan in ruminants risks formation of 3-methylindole
Commission Implementing Regulation (EU) 2026/1014, published on 8 May 2026, authorises until 28 May 2036 L-tryptophan (at least 98 % DM) from genetically modified E. coli CCTCC M 2024517 for all animal species, in feed and water for drinking. The additive composition includes a limit of 1,1′-ethylidene-bis-L-tryptophan (EBT) ≤ 10 mg/kg.
- Methods: identification according to the Food Chemicals Codex monograph; determination in the additive and premixtures — HPLC-FLD according to EN ISO 13904, in compound feed HPLC-FLD according to Regulation (EC) No 152/2009, in water for drinking HPLC-FLD. Endotoxins — Ph. Eur. 2.6.14, exposure up to 1 600 IU/m³ of air. In the Polish version of the act two footnotes to the annex (reference laboratory address and how endotoxin exposure is calculated) are printed in Latvian; the English version has them in English.
- EFSA data (5 batches): tryptophan 100.3–101.5 % DM, loss on drying 0–0.3 %, specific optical rotation −32.2 to −32.6° (Ph. Eur. −33.0 to −30.0°). In 3 batches EBT < 10 mg/kg, 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (MTCA) 0.6–0.7 mg/kg, endotoxins < 3 IU/mg, deoxynivalenol < 134–198.3 µg/kg. Neither viable cells nor DNA of the strain were detected (DNA limit of detection 1 ng/g).
- Dusting potential 1 904–2 115 mg/m³ (Stauber-Heubach); losses in premixture 0–14.3 % after 3 months, in pelleted feed 0–5.1 %, in water 0–5.3 % after 48 h at 20 °C; coefficient of variation of free tryptophan in pelleted feed 3.8 %.
- EFSA: the additive is safe for non-ruminant species; in ruminants ruminal metabolism of unprotected L-tryptophan may produce toxic quantities of 3-methylindole (skatole), which causes pulmonary disease in cattle and goats — the act requires protection against rumen degradation. Concerns about water for drinking (hygiene, nutritional balance); no conclusions on skin and eye irritation or skin sensitisation. The act: skin, eye and respiratory protection.