Effect of dilution, incubation time, and temperature of enrichment on cultural and PCR detection of Vibrio cholerae obtained from the oyster Crassostrea virginica.

The recovery of Vibrio cholerae 01 by culture from the oyster Crassostrea virginica and detection of the cholera toxin gene by polymerase chain reaction were evaluated using various enrichment procedures in alkaline peptone water. The effects of dilutions (1:10 and 1:100), incubation times (6-8 and 18-21 h), and incubation temperatures (35 and 42 degree) were determined. Recovery of V.cholerae was significantly greater (P<0.05) from oyster homogenates diluted 1:100 in alkaline peptone water and incubated at 42 degree C for 18-21 h. This enrichment procedure also provided the best detection of the cholera toxin gene by polymerase chain reaction.