Mucin degradation in human colon ecosystems

Bacteria in anaerobic human fecal cultures degrade the oligosaccharide and protein moieties of gut mutin glycoproteins, but most bacterial isolates from feces are unable to degrade mucin.In order to define better the bacterial populations that degrade gut mutins we have estimated their population densities in feces of 11 healthy subjects by a "most probable number" method.Tenfold serial dilutions of fresh feces were prepared, and triplicate cultures were inoculated with from 10s6 g to lo-" g feces into an anaerobic medium containing 2 mg/mJ hog gastric mutin.The most probable number per gram dry fecal weight of (a) total bacteria, (b) facultative anaerobes, (c) mucin oligosaccharide-degrading bacteria, and (d) mucin protein-degrading bacteria was estimated from the frequency of bacterial growth and mucin degradation among the triplicate cultures at each level of fecal inoculum.Mucin-degrading bacteria were present in feces from every subject.The mean + SD Jog,, most probable number of both mutin oligosaccharide-degrading and of mucin proteindegrading bacteria was 8.7 + 0.8, whereas the Jog,, most probable numbers of total bacteria and of facultative anaerobes were 10.7 + 0.5 and 7.8 2 1.1, respectively.There was no relationship between the presence of facultative anaerobes and mucin degradation.The most probable number of mucin-degrading bacteria was generally stable over periods of up