I. Arana et al., INFLUENCE OF A SURVIVAL PROCESS IN A FRESH-WATER SYSTEM UPON PLASMID TRANSFER BETWEEN ESCHERICHIA-COLI STRAINS, Microbial ecology, 33(1), 1997, pp. 41-49
Survival and potential ability to act as recipient or donor during the
survival process for one plasmid-free and four plasmid-bearing Escher
ichia coli strains under nonilluminated and illuminated conditions in
freshwater systems were studied. The five E. coli strains showed the s
ame behavior with respect to the microbial parameters used to characte
rize the survival process (culturability and viability). Under nonillu
minated conditions, recipient cells did not show variation in the abil
ity to receive and express plasmid material, while the culturability o
f the recipient strain remained stable. Under the same conditions, don
or cells lost their ability for plasmid transfer during the survival p
rocess, in all cases more than a 90% decrease of the number of transco
njugants was found after 4 days of experimentation, although viable an
d culturable cells of donor strains maintained the capacity to express
some plasmidic genes. Under illuminated conditions, transconjugants w
ere not detected after 2 days of experimentation. The number of transc
onjugants formed was dependent not only on the time donor strains rema
ined in the water but also on the temperature (20 or 37 degrees C) at
which the mating assays were conducted.