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Utilisation of protein by human gut bacteria

G.T. Macfarlane, C. Allison
DOI: http://dx.doi.org/10.1111/j.1574-6968.1986.tb01934.x 19-24 First published online: 1 May 1986


Mixed populations of human gut bacteria degraded cas casein by producing a variety of cell-bound and extracellular proteolytic enzymes. Casein was initially hydrolysed to TCA soluble peptides which were subsequently broken down to volatile fatty acids, ammonia, dicarboxylic acids and a range of phenolic compounds. Amino acids did not accumulate to any extent during casein breakdown, suggesting that the rate of peptide hydrolysis was the limiting step in protein utilisation by these bacteria. Similar fermentation products were produced from bovine serum albumin, however, the insoluble protein collagen was considerably more resistant to degradation by the colonic microflora, as evidenced by the reduced quantities of fermentation end-products formed.

  • Proteolysis
  • gut bacteria
  • fermentation products

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