Ecological studies of intestinal bacteria. Relation between the specificity of fecal ABO blood group antigen-degrading enzymes from enteric bacteria and the ABO blood group of the human host.

This report presents evidence for enteric bacterial adaptation to genetically controlled environmental factors in the individual human host. Human feces contains bacterial enzymes that degrade water-soluble A, B, and H antigens, and both the presence and the specificity of ABH blood group antigens in human gut mucous secretions are genetically determined for each individual. In this study, partially purified fecal blood group antigen-degrading enzymes from 31 subjects of known blood group and secretor status were obtained and their relative specificity for A, B, and H antigen was measured. Patterns of enzyme specificity were found that were related to the ABO blood type of each subject. This was most evident for enzyme preparations of blood group A, B, and AB secretors: enzyme preparations from group A secretors rapidly degraded A antigen but degraded B antigen only slightly during the same time interval; enzyme preparations from group B secretors degraded B antigen rapidly and A antigen only slightly, and enzyme preparations from group AB secretors degraded both A and B antigens. Bacterial adaptation of blood group A antigen-degrading enzyme activity was demonstrated in an in vitro anaerobic culture of fecal bacteria from a blood group B secretor.These findings are compatible with enteric bacterial adaptation of degradative enzymes to the genetically determined blood group antigens in their host's gut mucous secretions.