SELECTIVE IN-VITRO DEGRADATION OF THE SIALYLATED FRACTION OF GERM-FREE RAT MUCINS BY THE CECAL FLORA OF THE RAT

Mucins, which are synthesized throughout the gastrointestinal tract, m ay be degraded by the microflora of the large intestine. The present s tudy was undertaken to determine the differential fate of the various types of mucins. Mucins from germ-free rats were incubated in vitro in the presence of whole caecal flora from the conventional rat. Neutral , acidic and acidic sulphated mucins were spectrophotometrically assay ed over time upon anaerobic incubation. Sialylated mucins were more ra pidly degraded (90 %) than the other two types after 1 h and almost co mpletely within 4 h. Neutral and acidic sulphated mucins, with a 10-fo ld and 30-fold lower content than the sialylated fraction in the origi nal substrate, were more slowly degraded and to a lesser extent within 4 h, (55 and 40 %, respectively). The method used in the present stud y made it possible to investigate the activity of gut bacteria towards the various types of mucins. The degradation of the three mucin types was not uniform, the highest rate and extent of degradation being obs erved for sialylated mucins. (C) Inra/Elsevier, Paris.