The microbial feed additives regulated by Regulation
(EC) No. 1831/2003 and in accordance with the previous
guidelines are subjected to detailed safety assessment with
the intention of ensuring that they are innocuous to target
animals, users, and consumers. Particular attention is
focused on the presence of transmissible antibiotic resistance
markers, and the potential for production of harmful
metabolites. The guidelines do not diVerentiate between
species and strains with long histories of safe use and other
micro-organisms.