Safety of l-tryptophan technically pure, produced by Escherichia coli CGMCC 3667, for all animal species based on a dossier submitted by GBT Europe GmbH

nutritional additive, amino acids and their salts and analogues, L-tryptophan, safety, efficacy, genetically modified microorganisms
First published in the EFSA Journal
6 March 2017
25 January 2017
Scientific Opinion


l-Tryptophan, technically pure, is a feed additive produced by fermentation with a genetically modified strain of Escherichia coli. The Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) of EFSA, issued two opinions on the safety and efficacy of the product, in which it could not conclude on the safety of this additive for target animals, consumer, user and the environment, due to the insufficient characterisation of the genetic modification. The European Commission asked the Authority to deliver an opinion on the safety of l-tryptophan, technically pure, as a nutritional additive for all animal species based on additional data submitted by the applicant. Based on new information provided on the genetic modification, including the presence/absence of antibiotic resistance genes in the production strain, the FEEDAP Panel concludes that the l-tryptophan is safe for target animals, consumers, users and the environment.

Panel members at the time of adoption

Gabriele Aquilina, Giovanna Azimonti, Vasileios Bampidis, Maria de Lourdes Bastos, Georges Bories, Andrew Chesson, Pier Sandro Cocconcelli, Gerhard Flachowsky, Jürgen Gropp, Boris Kolar, Maryline Kouba, Marta López-Alonso, Secundino López Puente, Alberto Mantovani, Baltasar Mayo, Fernando Ramos, Guido Rychen, Maria Saarela, Roberto Edoardo Villa, Robert John Wallace and Pieter Wester.
Panel on Additives and Products or Substances used in Animal Feed
feedap [at]
EFSA Journal 2017;15(3):4705
Question Number
On request from
European Commission