Antigenic Diversity of Methanogenic Bacteria from Intestinal Tracts of Animals

Abstract

The immunologic relationships of methanogens isolated from animal feces and rumen contents to currently accepted genera and species were investigated. A comprehensive panel of calibrated polyclonal antibody probes for 29 reference organisms of almost all genera was used to determine the antigenic fingerprints of the isolates. A comparative analysis of the antigenic fingerprints showed distinctive features for isolates of different animals and, consequently, a considerable antigenic diversity, larger than that previously observed among human islates. The isolates from rumen contents were immunologically related to Metbanobrevibacter arboriphilus DC but were unrelated to Metbanobrevibacter ruminantium M1, whether or not the isolates required coenzyme M. Most isolates from Wistar rats and an isolate from goose feces reacted with probes for reference organisms classified as Metbanobrevibacter smithii , the predominant methanogen in human feces. Isolates from feces of sheep, cow, horse, and pig did not react with any of the probes currently available, indicating that the isolates are of immunotypes different from those of the reference organisms. Isolates from chicken and turkey feces were immunologically related to the genus Methanogenium as shown also by physiologic and cell-wall chemical studies, but were not closely related to the reference methanogens Methanogenium marisnigri JRlm or cariaci JRlc. Thus, the methanogens in chicken and turkey are of immunotypes different from those of the reference Methanogenium species isolated from marine environments.