title: Microbial contamination of embryos and semen during long term banking in liquid nitrogen.
abstract: We report on microbial contamination of embryos and semen cryopreserved in sealed plastic straws and stored for 6-35 years in liquid nitrogen. There were 32 bacterial and 1 fungal species identified from randomly drawn liquid nitrogen, frozen semen, and embryos samples stored in 8 commercial and 8 research facility liquid nitrogen (LN) tanks. The identified bacteria represented commensal or environmental microorganisms and some, such as Escherichia coli, were potential or opportunistic pathogens for humans and animals. Stenotrophomonas maltophilia was the most common contaminant identified from the samples and was further shown to significantly suppress fertilization and embryonic development in vitro. Analysis of the strains by pulsed field gel electrophoresis revealed restriction patterns with no relatedness indicating that there was no apparent cross-contamination of S. maltophilia strains between the germplasm and liquid nitrogen samples. In addition, no transmission of bovine viral diarrhea virus (BVDV) and bovine herpesvirus-1 (BHV-1) from infected semen and embryos straws to clean germplasm stored in the same LN tanks or LN was detected.
authors.affiliation: Canadian Food Inspection Agency, Animal Diseases Research Institute, Germplasm Centre of Expertise, Ottawa Laboratory-Fallowfield, K2H 8P9, Ottawa/Nepean, Ont., Canada. bielanskia@inspection.gc.ca
authors.forename: A
authors.initials: A
authors.lastname: Bielanski
authors.forename: H
authors.initials: H
authors.lastname: Bergeron
authors.forename: P C K
authors.initials: PC
authors.lastname: Lau
authors.forename: J
authors.initials: J
authors.lastname: Devenish
mesh_terms: D000818:Animals; D002417:Cattle; D015925:Cryopreservation; D001908:Diarrhea Viruses, Bovine Viral / Q000302:isolation & purification; D004622:Embryo, Mammalian / Q000382:microbiology*; D004866:Equipment Contamination; D007242:Herpesvirus 1, Bovine / Q000302:isolation & purification; D009584:Nitrogen; D012661:Semen / Q000382:microbiology*; D013081:Sperm Motility; D020615:Stenotrophomonas maltophilia / Q000302:isolation & purification; D014015:Tissue Banks
chemical_list: D009584:Nitrogen