Safety of l‐tryptophan produced using Escherichia coli CGMCC 11674 for all animal species

nutritional additive, amino acid, l‐tryptophan, safety, Escherichia coli CGMCC 11674
First published in the EFSA Journal
10 Junio 2020
25 Mayo 2020
Scientific Opinion

Legal notice: 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 FEEDAP Panel issued an opinion in 2019 in which they could not conclude on the safety of the additive for the target animals and for the consumer due to tryptophan‐related impurities such as 1,1′‐ethylidene‐bis‐l‐tryptophan (EBT). The applicant submitted additional data and the European Commission (EC) has requested EFSA to deliver a new opinion on the safety of the additive under assessment. The manufacturing process has been adjusted to reduce the amount of tryptophan‐related impurities and the analysis of three new batches of the additive indicated that levels of EBT and 1‐methyl‐1,2,3,4‐tetrahydro‐β‐carboline‐3‐carboxylic acid (MTCA) represent no safety concerns for the target species or for the consumer.

Panel members at the time of adoption

Giovanna Azimonti, Vasileios Bampidis, Maria de Lourdes Bastos, Henrik Christensen, Birgit Dusemund, Mojca Kos Durjava, Maryline Kouba, 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 2020;18(6):6168
Question Number
On request from
European Commission