Safety and efficacy of l‐tryptophan produced by fermentation with Escherichia coli CGMCC 7.248 for all animal species

nutritional additive, amino acid, L-tryptophan safety, efficacy, genetically modified microorganism
First published in the EFSA Journal
28 February 2019
22 January 2019
Scientific Opinion

Relevant information or parts of this scientific output have been blackened in accordance with the confidentiality requests formulated by the applicant pending a decision thereon by the European Commission. The full output has been shared with the European Commission, EU Member States and the applicant. The blackening will be subject to review once the decision on the confidentiality requests is adopted by the European Commission.


Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on l‐tryptophan produced by fermentation with a genetically modified strain of Escherichia coli CGMCC 7.248 when used as a nutritional additive in feed and water for drinking for all animal species and categories. The production strain E. coli CGMCC 7.248 and its recombinant DNA were not detected in the final product. The product l‐tryptophan, manufactured by fermentation with E. coli CGMCC 7.248, does not give rise to any safety concern with regard to the genetic modification of the production strain. l‐Tryptophan produced by E. coli CGMCC 7.248 is safe for non‐ruminant target species. The use of unprotected l‐tryptophan in ruminant feed should be avoided. l‐Tryptophan produced by fermentation by E. coli CGMCC 7.248 is safe for the consumer. The level of endotoxins present in the product and its dusting potential indicate an inhalation risk for the user. l‐Tryptophan produced by E. coli CGMCC 7.248 is not a skin or eye irritant but it is a dermal sensitiser. The use of l‐tryptophan produced by E. coli CGMCC 7.248 in animal nutrition does not pose a risk to the environment. The product under assessment is regarded as an effective source of the amino acid l‐tryptophan for all non‐ruminant species. For the supplemental l‐tryptophan to be as efficacious in ruminants as in non‐ruminant species, it requires protection against degradation in the rumen.

Cas: 73-22-3
Inchi: InChI=1S/C11H12N2O2/c12-9(11(14)15)5-7-6-13-10-4-2-1-3-8(7)10/h1-4,6,9,13H,5,12H2,(H,14,15)/t9-/m0/s1
Iupac: (2S)-2-amino-3-(1H-indol-3-yl)propanoic acid

Panel members at the time of adoption

Giovanna Azimonti, Vasileios Bampidis, Maria de Lourdes Bastos, Henrik Christensen, Birgit Dusemund, Maryline Kouba, Mojca Kos Durjava, Marta López‐Alonso, Secundino López Puente, Francesca Marcon, Baltasar Mayo, Alena Pechová, Mariana Petkova, Fernando Ramos, Yolanda Sanz, Roberto Edoardo Villa and Ruud Woutersen.
Panel on Additives and Products or Substances used in Animal Feed
feedap [at]
EFSA Journal 2019;17(2):5601
Question Number
On request from
European Commission