ISOLATION OF METHANOBREVIBACTER-SMITHII FROM HUMAN FECES

Fecal specimens from 9 adults were examined for the presence of methanogenic bacteria. Enrichment cultures of 5 specimens produced methane in 5 days. Of these 5 specimens, 3 were tested and produced methane during a short-term incubation. Four specimens did not produce methane in short-term incubation or in enrichment culture. Each methanogenic enrichment culture contained methanogens similar in morphology to organisms of the genus Methanobrevibacter and showed factor-420 fluorescence by fluorescence microscopy. Pure cultures were obtained from 4 of the 5 methanogenic enrichment cultures. Each isolate grew and formed methane from H2-CO2 or formate, but growth obtained with formate was poor. None of the isolates used acetate, methanol or trimethylamine. All isolates grew in the presence of bile salts. In immunological studies, each isolate was closely related to the type strain of M. smithii, a finding consistent with the physiological and morphological similarities between the isolates and the type strain.