Human Indigenous Microflora in Gnotobiotic Rats

WHILE the existence of a symbiotic relationship between man or animals and micro-organisms was recognized as early as the times of Pasteur and Metchnikoff 1 , little is known concerning the evolution, complete identification, survival factors and the mechanisms which control the beneficial or pathogenic activities of the intestinal flora. Recently, however, model systems for examination of the intestinal flora have been made available in the establishment of germ-free 2 , gnotobiotic (known flora) 2 and specific pathogen-free (SPF) animals 3 .