Phylogenetic distribution of genes encoding β-glucuronidase activity in human colonic bacteria and the impact of diet on faecal glycosidase activities

Freda Mabel McIntosh, Nathalie Maison, Grietje Holtrop, Pauline Young, Valerie Joan Stevens, Jennifer Ince, Alexandra Mary Johnstone, Gerald Lobley, Harry James Flint, Petra Louis (Corresponding Author)

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Bacterial ß-glucuronidase in the human colon plays an important role in cleaving liver conjugates of dietary compounds and xenobiotics, while other glycosidase activities are involved in the conversion of dietary plant glycosides. Here we detected an increase in ß-glucuronidase activity in faecal samples from obese volunteers following a high-protein moderate carbohydrate weight-loss diet, compared with a weight maintenance diet, but little or no changes were observed when the type of fermentable carbohydrate was varied. Other faecal glycosidase activities showed little or no change over a fivefold range of dietary NSP intake, although a-glucosidase increased on a resistant starch-enriched diet. Two distinct groups of gene, gus and BG, have been reported to encode ß-glucuronidase activity among human colonic bacteria. Degenerate primers were designed against these genes. Overall, Firmicutes were found to account for 96% of amplified gus sequences, with three operational taxonomic units particularly abundant, whereas 59% of amplified BG sequences belonged to Bacteroidetes and 41% to Firmicutes. A similar distribution of operational taxonomic units was found in a published metagenome dataset involving a larger number of volunteers. Seven cultured isolates of human colonic bacteria that carried only the BG gene gave relatively low ß-glucuronidase activity that was not induced by 4-nitrophenyl-ß-Dglucuronide. By comparison, in three of five isolates that possessed only the gus gene, ß-glucuronidase activity was induced.
Original languageEnglish
Pages (from-to)1876-1887
Number of pages12
JournalEnvironmental Microbiology
Issue number8
Early online date24 Feb 2012
Publication statusPublished - 2012


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