Abstract
A new most-probable-number (MPN) method using 96-well microtiter plates was developed to enumerate denitrifying bacteria. In this method, dilutions of samples are added to microtiter plates with a medium and incubated anaerobically using the AnaeroPouch culture system (Mitsubishi Gas Chemical, Inc., Tokyo, Japan). The microtiter plate MPN method gave precise estimates of the population densities of a culture of Paracoccus denitrificans, similar to the estimates obtained using a test tube MPN method and a colony count method. The population densities of denitrifying bacteria in soil samples estimated by the microtiter plate MPN method were higher than the population densities estimated by the test tube MPN method. Because the new method requires less equipment, labor, and time than the conventional test tube method. It will be valuable for estimating the biomass of denitrifying bacteria in natural samples.
