title: Viability and stability of Escherichia coli and enterococci populations in fecal samples upon freezing.
abstract: We studied the survival of Escherichia coli and enterococci populations in fecal samples of 7 host species after storage at -20 and -80 °C for 30 days. Composite fecal samples were collected from cows, chickens, horses, pigs, dogs, birds, and humans, and bacteria were enumerated before and after storage. Twenty-eight colonies of each bacterial species were typed before and after storage and the strains were assigned to different biochemical phenotypes (BPTs). A significant reduction in the number of E. coli was observed in all samples stored at -20 °C but in only 3 of those samples stored at -80 °C. However, the numbers of enterococci were similar in most stored samples (except cow and birds). The number and the distribution of E. coli and enterococci BPTs in fresh samples did not vary significantly from those stored at either temperature. Furthermore, the population structure of E. coli and enterococci did not change significantly after storage at -80 °C, this was always the case for those samples stored at -20 °C. We conclude that for those studies investigating E. coli or enterococci population structure, short-term storage (≤ 30 days) of fecal samples in a glycerol broth at -80 °C is a preferable option.
authors.affiliation: a GeneCology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland, Australia.
authors.forename: N
authors.initials: N
authors.lastname: Masters
authors.affiliation: b School of Biomolecular and Physical Sciences, Griffith University, Nathan, Queensland, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Christie
authors.affiliation: b School of Biomolecular and Physical Sciences, Griffith University, Nathan, Queensland, Australia.|c Smart Water Research Centre, Griffith University, Gold Coast, Queensland, Australia.
authors.forename: H
authors.initials: H
authors.lastname: Stratton
authors.affiliation: a GeneCology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland, Australia.|c Smart Water Research Centre, Griffith University, Gold Coast, Queensland, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Katouli
mesh_terms: D000818:Animals; D001717:Birds; D002417:Cattle; D002645:Chickens; D004285:Dogs; D016983:Enterococcus / Q000254:growth & development*; D004926:Escherichia coli / Q000254:growth & development*; D005243:Feces / Q000737:chemistry / Q000382:microbiology*; D005260:Female; D005615:Freezing; D006736:Horses; D006801:Humans; D050296:Microbial Viability; D010641:Phenotype; D013552:Swine
keywords: PhP typing; bacterial composition; composition bactérienne; deep freezing; diversity; diversité; population structure; structure démographique; surgélation; typage PhP