Scientific Opinion on the safety and efficacy of L-tryptophan produced by Escherichia coli (FERM BP-11354) for all animal species, based on a dossier submitted by Ajinomoto Eurolysine S.A.S.

L-Tryptophan, technically pure, is a feed additive produced by a genetically modified Escherichia coli strain (FERM BP-11354). Neither the production strain nor its recombinant DNA were detected in the final product. L-Tryptophan manufactured by fermentation with E. coli FERM BP-11354 does not give rise to any safety concern for the genetic modifications of the production strain. The L-tryptophan product produced by E. coli (FERM BP-11354) is considered safe for non-ruminant target species when used to supplement the diet in appropriate amounts. The use of unprotected L-tryptophan in ruminants’ feed should be avoided. L-Tryptophan will be incorporated into proteins of the body of the target animal and any potential excess will be metabolised and excreted. Considering the high purity of the product under assessment, no risks are expected for the consumer from the use of L-tryptophan produced by E. coli (FERM BP-11354) as a feed additive. Safety is further ensured by the low levels (less than 10 mg/kg additive each) of 1,1-ethylidene-bis-L-tryptophan (EBT) and 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (MTCA), previously seen to cause eosinophilia–myalgia syndrome in humans. The FEEDAP Panel considers that the product is not an irritant to the skin or eyes and it is not likely to be a skin sensitiser. Although there is a potential for user exposure by inhalation, there is no evidence of acute toxicity by the inhalation route. L-Tryptophan is a naturally occurring amino acid and its use in animal nutrition is not expected to be of concern to the environment. The additive L-tryptophan is regarded as an effective source of the amino acid L-tryptophan. Supplemental L-tryptophan is degraded by ruminal microorganisms if not given in a protected form.