title: Survival of Escherichia coli strains in Mediterranean brackish water in the Bizerte lagoon in northern Tunisia.
abstract: This study investigated survival and virulence of Escherichia coli strains exposed to natural conditions in brackish water. Two E. coli strains (O126:B16 and O55:B5) were incubated in water microcosms in the Bizerte lagoon in northern Tunisia and exposed for 12 days to natural sunlight in June (231 to 386 W/m2, 26 +/- 1 degrees C, 30 g/L) and in April (227 to 330 W/m2, 17 +/- 1 degrees C, 27 g/L) or maintained in darkness for 21 days (17 +/- 1 degrees C, 27 g/L). The results revealed that sunlight was the most significant inactivating factor (decrease of 3 Ulog within 48 hours for the two strains) compared to salinity and temperature (in darkness). Survival time of the strains was prolonged as they were maintained in darkness. Local strain (E. coli O55:B5) showed better survival capacity (T90 = 52 hours) than E. coli O126:B16 (T90 = 11 h). For both, modifications were noted only for some metabolic activities of carbohydrates hydrolysis. Cytotoxicity of the two strains, tested on Vero cell, was maintained during the period of survival.
authors.affiliation: National Institute of Sea Sciences and Technology, Laboratory of Microbiology, Salammbô, Tunisia.
authors.forename: I
authors.initials: I
authors.lastname: Boukef
authors.forename: M
authors.initials: M
authors.lastname: El Bour
authors.forename: N
authors.initials: N
authors.lastname: Al Gallas
authors.forename: O
authors.initials: O
authors.lastname: El Bahri
authors.forename: S
authors.initials: S
authors.lastname: Mejri
authors.forename: R
authors.initials: R
authors.lastname: Mraouna
authors.forename: R
authors.initials: R
authors.lastname: Ben Aissa
authors.forename: A
authors.initials: A
authors.lastname: Boudabous
authors.forename: P
authors.initials: P
authors.lastname: Got
authors.forename: M
authors.initials: M
authors.lastname: Troussellier
mesh_terms: D004784:Environmental Monitoring; D004926:Escherichia coli / Q000502:physiology*; D008522:Mediterranean Sea; D013997:Time Factors; D014416:Tunisia; D014867:Water / Q000737:chemistry*; D014871:Water Microbiology; D014873:Water Pollutants
chemical_list: D014873:Water Pollutants; D014867:Water