I. Arana et al., DETECTION AND ENUMERATION OF VIABLE BUT NON-CULTURABLE TRANSCONJUGANTS OF ESCHERICHIA-COLI DURING THE SURVIVAL OF RECIPIENT CELLS IN RIVER WATER, Journal of applied microbiology, 83(3), 1997, pp. 340-346
Viable but non-culturable transconjugant cells were detected by a modi
fication of the direct viable count (DVC) method, This modification in
volved the addition of parental antimicrobial markers (kanamycin and s
treptomycin) to the elongation medium in order to promote selective el
ongation of the transconjugant cells, Presence of viable, other than c
ulturable, transconjugants was demonstrated in matings with parental c
ells from TSB culture as well as with recipient cells from survival in
river water (under illuminated and non-illuminated systems). In matin
gs with a recipient strain from illuminated systems, culturable transc
onjugants were not detected after the third day of recipient cell surv
ival, In spite of this, viable transconjugants were detected in number
s that exceeded 10(5) cells ml(-1). These results clearly show that a
fraction of non-culturable recipient cells is able to receive and expr
ess plasmids by conjugation processes and form viable but non-culturab
le transconjugant cells.