Safety and efficacy of l‐tryptophan produced with Escherichia coli CGMCC 11674 for all animal species

nutritional additive, amino acid,L-tryptophan, safety, efficacy,Escherichia coli
First published in the EFSA Journal
21 March 2019
26 February 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 Escherichia coli CGMCC 11674 when used as a nutritional additive in feed and water for drinking for all animal species and categories. The production strain did not raise safety concerns. The FEEDAP Panel cannot conclude on the safety of l‐tryptophan produced by E. coli CGMCC 11674 for the target species and for the consumer due to the tryptophan‐related impurities such as 1,1’‐ethylidene‐bis‐l‐tryptophan (EBT). The FEEDAP Panel has concerns on the safety of the simultaneous oral administration of l‐tryptophan via water for drinking and feed. Using unprotected forms of tryptophan in ruminants can be a risk. The FEEDAP Panel cannot conclude on the dermal or ocular irritation and skin sensitisation of l‐tryptophan produced by E. coliCGMCC 11674. The additive poses a risk by inhalation from the exposure to endotoxins for people handling the additive. The use of l‐tryptophan produced by E. coli CGMCC 11674 in animal nutrition does not pose a risk to the environment. The additive under assessment is regarded as an effective source of the amino acid l‐tryptophan for all non‐ruminant species. If the product l‐tryptophan is intended for use in ruminants, it should be protected from ruminal degradation.

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]
Question Number
On request from
European Commission