Safety of l-tryptophan technically pure, produced by fermentation with Escherichia coli DSM 25084, KCCM 11132P and SARI12091203 for all animal species based on a dossier submitted by FEFANA Asbl

nutritional additive, amino acids, L-tryptophan, safety, efficacy, genetically modified microorganisms
First published in the EFSA Journal
28 February 2017
25 January 2017
Scientific Opinion


In 2015, the EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) issued an opinion on the safety and efficacy of l-tryptophan produced by fermentation using three strains of Escherichia coli, when used as a nutritional additive for all animal species. The Panel concluded that the safety of l-tryptophan produced by E. coli SARI12091203 for target animals, consumers, users and the environment could not be assessed because the data submitted did not permit the identity and safety of the strain, and the purity of the additive, to be determined. During the current assessment, the applicant withdrew the application for l-tryptophan produced by E. coli SARI12091203. l-Tryptophan produced by E. coli DSM 25084 or KCCM 11132P was considered safe for non-ruminant target species, the consumer and the environment. For both products, the level of endotoxins and the possible dusting potential indicated a risk by inhalation for the user. In the absence of data, a potential for dermal sensitisation could not be excluded. The Commission gave the applicant the possibility of submitting complementary information to allow the FEEDAP Panel to complete its assessment. The additional data on the characterisation of the additives and on their potential for inhalation toxicity and as skin sensitisers are the subject of the current opinion. Due to improvements in the manufacturing process, the level of endotoxins present in the l-tryptophan produced by E. coli KCCM 11132P has been markedly reduced; consequently, the endotoxin content does not represent a health risk for the user. The additive has a low acute toxicity by inhalation and is not considered as a potential skin sensitiser. l-Tryptophan produced by E. coli DSM 25084 is not considered a skin sensitiser. The level of endotoxins in this product, however, represents a risk by inhalation for the user handling the additive.

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(2):4712
Question Number
On request from
European Commission