L-tryptophan from Escherichia coli CGMCC 7.460 (3c442): HPLC-FLD according to EN ISO 13904, EBT at most 10 mg/kg, dusting potential up to 12.9 g/m³ — EFSA calculated 2 150 IU of endotoxins per working day against a threshold of 900 IU, the act limits exposure to 1 600 IU/m³
Commission Implementing Regulation (EU) 2025/188, published on 3 February 2025, authorises until 23 February 2035 L-tryptophan produced with the non-genetically modified strain E. coli CGMCC 7.460 (a K-12 derivative) as a nutritional additive for all animal species, in feed and in water for drinking. It is based on the EFSA opinion of 12 March 2024 (applicant: Kempex Holland B.V.).
- Specification: powder with at least 98 % tryptophan on a dry matter basis and at most 0.5 % water; 1,1′-ethylidene-bis-L-tryptophan (EBT) at most 10 mg/kg. Methods: identification according to the Food Chemical Codex L-tryptophan monograph; quantification in the additive and premixtures — high-performance liquid chromatography with fluorescence detection (HPLC-FLD) according to EN ISO 13904; in compound feed HPLC-FLD according to Regulation (EC) No 152/2009. Endotoxins according to Ph. Eur. 2.6.14.
- EFSA data: five batches averaged 99.8 % tryptophan in DM (99.2–101.5 %), specific optical rotation of three batches −30.8 to −31.9° (Ph. Eur.: −30.0 to −33.0°). Arsenic up to 0.071 mg/kg, lead up to 0.011 mg/kg, cadmium and mercury below the LOQ; aflatoxins 1.6–2.3 μg/kg, other mycotoxins below the limits of detection. EBT below 10 mg/kg (LOD) in all three batches; MTCA is reported as below 0.1 mg/kg (LOD) in the characterisation section and as below 1 mg/kg in the consumer safety section.
- Stability: no losses in the additive after 6 months, losses of 8–14 % in a piglet premixture after 6 months; pelleting at 73–75 °C without losses, after 3 months losses of 5–7.3 % in mash and 4.8–4.9 % in pelleted feed, in water 1.5–2.9 % after 48 h at 20 °C. The coefficient of variation of total tryptophan in 10 subsamples was 2 %, and after subtracting the feed’s protein-bound tryptophan (0.23 %) — 5 %.
- Users: endotoxins below 300 IU/g, but dusting potential 10.1–12.9 g/m³ (Stauber-Heubach) — in a worst-case scenario 2 150 IU per working day against a threshold of 900 IU, so the act requires the endotoxin content and dusting potential to give an exposure of at most 1 600 IU/m³ of air. EFSA: unprotected tryptophan in ruminants may increase production of toxic skatole (3-methylindole), hence the obligation of rumen protection; the label must warn about the supply of essential amino acids when given in water.