EU Assesses Threonine Produced by E. coli strains NRRL B-30843, DSM 26131, KCCM11133P or DSM 25085

Following a request from the European Commission, the European Food Safety Authority (EFSA) Panel on Additives and Products or Substances used in Animal Feed (FEEDAP Panel) was asked to deliver a scientific opinion on L-threonine produced by fermentation with genetically modified (GM) strains of Escherichia coli K-12 (NRRL B-30843, DSM 26131, KCCM11133P) or with a non-GM E. coli strain (DSM 25085) for all animal species.



L-Threonine is an essential amino acid for all animal species. It is commonly considered the second and third limiting amino acid in cereaL-based diets for pigs and poultry, respectively. It is widely used in the feed industry to optimise dietary protein.



Three of the strains are GM: E. coli NRRL B-30843, E. coli DSM 26131 and E. coli KCCM11133P. The final product obtained from E. coli strain NRRL B-30843 contains no cultivable production organisms or recombinant DNA. The product from E. coli strain KCCM11133P contains no cultivable production organisms, but the possible presence of fragments spanning the full length of recombinant genes cannot be ruled out. However, no genes of concern remain in the production strain KCCM11133P. No safety concerns were found in these two products related to the genetic modification. The genetic modification of E. coli DSM 26131 and its possible consequences for the product could not be assessed because of insufficient data.



L-Threonine products made by fermentation with E. coli strains NRRL B-30843, KCCM11133P or DSM 25085 are free of the production strain and have a high purity (= 98.8 %). No recombinant DNA could be detected in L-threonine produced by fermentation of the GM strains E. coli NRRL B-30843 and KCCM11133P.



L-Threonine, technically pure, produced by E. coli NRRL B-30843, KCCM11133P or DSM 25085 strains is safe for the target animals when used in appropriate amounts to supplement feed to compensate for threonine deficiency in feedingstuffs. However, the FEEDAP Panel has concerns regarding the safety of the simultaneous oral administration of L-threonine via water for drinking and feed.



Since the composition of tissues and products of animal origin will not be changed by the use of l-threonine in animal nutrition, and considering the high purity of the products made by E. coli strains NRRL B-30843, KCCM11133P and DSM 25085, no risks are expected for the consumer from their use as a feed additive.



The FEEDAP Panel considers that L-threonine produced by E. coli strains NRRL B-30843, KCCM11133P or DSM 25085 is not an irritant to eyes and skin, and is not a skin sensitiser. There is no risk from inhalation of L-threonine but concerns may arise from the content of endotoxins in the products.



The use of the product L-threonine produced by E. coli strains NRRL B-30843, KCCM11133P or DSM 25085 in animal nutrition does not pose a risk to the environment.



The L-threonine products are considered an efficacious source of the amino acid L-threonine for all animal species. For L-threonine to be as efficacious in ruminants as in non-ruminant species, it requires protection against degradation in the rumen.



L-Threonine produced by thegenetically modified microorganism (GMM) E. coli DSM 26131 could not be assessed because of the insufficient molecular characterisation of the genetic modification, and the lack of data on both the absence of the production strain and its recombinant DNA from the final product. In particular, the EFSA FEEDAP Panel could not conclude on the safety of this product for target animals, and on the safety concerning consumers, users and the environment.