Quantitative and specific detection of a trichloroethylene-degrading methanotroph, Methylocystis sp. strain M, by a most probable number-polymerase chain reaction method.

We developed a rapid and specific enumeration method for a trichloroethylene-degrading methanotroph, Methylocystis sp. strain M, based on a most probable number-polymerase chain reaction method for monitoring the bacterium at bioremediation sites. The primers designed for the mmoC gene of the soluble methane monooxygenase gene cluster were specific to strain M. Recovery of the cells with a membrane filter enabled us to detect strain M in trichloroethylene-contaminated groundwater. We used the enumeration method to monitor the number of strain M cells in effluent from soil columns supplied with trichloroethylene-contaminated groundwater. The number of strain M cells in the effluent depended on the amount of the strain M inoculated and the number of cells measured by the most probable number-polymerase chain reaction method was correlated with that measured by a culture method. The detection limit for strain M in effluent detected by MPN-PCR method was 4 to 8 x 10(2) cells/ml.