Isolation of catechin-converting human intestinal bacteria
Article first published online: 4 MAY 2011
© 2011 The Authors. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology
Journal of Applied Microbiology
Volume 111, Issue 1, pages 165–175, July 2011
How to Cite
Kutschera, M., Engst, W., Blaut, M. and Braune, A. (2011), Isolation of catechin-converting human intestinal bacteria. Journal of Applied Microbiology, 111: 165–175. doi: 10.1111/j.1365-2672.2011.05025.x
- Issue published online: 13 JUN 2011
- Article first published online: 4 MAY 2011
- Accepted manuscript online: 1 APR 2011 05:46AM EST
- 2011/0301: received 21 February 2011, revised 25 March 2011 and accepted 27 March 2011
- anaerobic metabolism;
- Clostridium orbiscindens;
- Eggerthella lenta;
- Flavonifractor plautii
Aims: To isolate and characterize bacteria from the human intestine that are involved in the conversion of catechins, a class of bioactive polyphenols abundant in the human diet.
Methods and Results: Two bacterial strains, rK3 and aK2, were isolated from an epicatechin-converting human faecal suspension. The isolates catalysed individual steps in the degradation of (−)-epicatechin and (+)-catechin. Based on their phenotypic characteristics and 16S rRNA gene sequences, the isolates were identified as Eggerthella lenta and Flavonifractor plautii (formerly Clostridium orbiscindens). Eggerthella lenta rK3 reductively cleaved the heterocyclic C-ring of both (−)-epicatechin and (+)-catechin giving rise to 1-(3,4-dihydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)propan-2-ol. The conversion of catechin proceeded five times faster than that of epicatechin. Higher (epi)catechin concentrations led to an accelerated formation of the ring fission product without affecting the growth of Eg. lenta rK3. Flavonifractor plautii aK2 further converted 1-(3,4-dihydroxyphenyl)-3-(2,4,6-trihydroxyphenyl)propan-2-ol to 5-(3,4-dihydroxyphenyl)-γ-valerolactone and 4-hydroxy-5-(3,4-dihydroxyphenyl)valeric acid. Flavonifractor plautii DSM 6740 catalysed the identical reaction indicating it is not strain specific.
Conclusions: The conversion of dietary catechins by the isolated Eg. lenta and F. plautii strains in the human intestine may affect their bioavailability.
Significance and Impact of the Study: The majority of catechin metabolites are generated by the intestinal microbiota. The identification of catechin-converting gut bacteria therefore contributes to the elucidation of the bioactivation and the health effects of catechins.