title: Safety and risk assessment of the genetically modified Lactococci on rats intestinal bacterial flora.
abstract: The interaction between Lactococcus lactis NZ9000/pNZPNK and intestinal microflora was evaluated as a method to assess safety of genetically modified microorganisms (GMMs). L. lactis NZ9000/pNZPNK is one kind of GMM and able to produce the intracellular subtilisin NAT (nattokinase) under induction with nisin. The host strain L. lactis NZ9000 was a generally recognized as safe (GRAS) microorganism. Six groups of Wistar rats were orally administered with L. lactis NZ9000/pNZPNK and L. lactis NZ9000 for 6 weeks. Fecal and cecal contents were collected to determine the number of L. lactis NZ9000, L. lactis NZ9000/pNZPNK, Lactobacillus, coliform bacteria, beneficial bacteria Bifidobacterium and harmful bacteria Clostridium perfringens. The liver, spleen, kidney and blood were evaluated for the bacterial translocation. After 6 weeks consumption with GM and non-GM Lactococcus, no adverse effects were observed on the rat's body weight, hematological or serum biochemical parameters, or intestinal microflora. The bacterial translocation test showed that L. lactis NZ9000/pNZPNK did not translocate to any organ or blood. Bifidobacterium was significantly increased in feces after administration of both Lactococcus strains (L. lactis NZ9000 and L. lactis NZ9000/pNZPNK), while C. perfringens remained undetectable during the experiment. These results suggested that L. lactis NZ9000/pNZPNK could be safe in animal experiments and monitoring of the interaction between test strains and intestinal microflora might be applied as a method for other GMM safety assessments.
authors.affiliation: Institute of Microbiology and Biochemistry, College of Life Science, National Taiwan University, Taipei, Taiwan.
authors.forename: Kai-Chien
authors.initials: KC
authors.lastname: Lee
authors.forename: Chin-Feng
authors.initials: CF
authors.lastname: Liu
authors.forename: Tzu-Hsing
authors.initials: TH
authors.lastname: Lin
authors.forename: Tzu-Ming
authors.initials: TM
authors.lastname: Pan
mesh_terms: D000818:Animals; D018988:Bacterial Translocation; D007422:Intestines / Q000382:microbiology*; D017045:Lactococcus / Q000235:genetics* / Q000502:physiology; D008297:Male; D051381:Rats; D017208:Rats, Wistar