Ecological studies of microbes introduced into the environment have been limited by the lack of sensitive and specific methods for detection and identification of released organisms among the myriad of other microbes present in nature. Similar difficulties exist for detection of DNA transfer from a released organism to other microbes in the environment. Techniques generating viable counts of specific microbes from environmental samples are among the best available for ecological studies of microorganisms released into the environment. Antiserum that is specific to certain species or strains of bacteria from environmental samples by immunoisolation techniques. Immunoisolation can detect a few cells of certain bacterial pathogens in a milliliter of seed extract. The application of immunoisolation and viable count methods to detection of released microbes in soil or on plant roots was an objective of the study.