Safety evaluation of the food enzyme β-cyclodextrin glucanotransferase from Escherichia coli strain WCM105xpCM6420

The food enzyme β-cyclodextrin glucanotransferase ((1→4)-α-d-glucan 4-α-d-[(1→4)-α-d-glucano]-transferase; EC 2.4.1.19) is produced with a genetically modified Escherichia coli strain WCM105xpCM6420 by Wacker Chemie GmbH. The production strain harbours a self-replicating multicopy plasmid which contains genes conferring resistance to two highly important antimicrobials for human and veterinary medicine. The food enzyme is free from viable cells of the production organism, but not of its recombinant DNA. Therefore, the food enzyme poses a risk of promoting the spread of antimicrobial resistance genes. It is intended to be used in starch processing for the production of γ-cyclodextrin. Residual amounts of total organic solids are removed by the purification steps applied during the production of γ-cyclodextrin; consequently, dietary exposure was not calculated. A bacterial reverse mutation test was not considered, because the representativeness of the test material could not be established. No other toxicological tests were provided. In the absence of information about the sequence homology of this β-cyclodextrin glucanotransferase with known allergens, the Panel could not complete the assessment on the allergenicity of the food enzyme. The Panel concludes that the food enzyme β-cyclodextrin glucanotransferase produced with the genetically modified E. coli strain WCM105xpCM6420 cannot be considered safe.