Competition in the Metabolism of Glycyrrhizin with Glycyrrhetic Acid Mono-Glucuronide by Mixed Eubacterium sp. GLH and Ruminococcus sp. PO1-3

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Eubacterium sp. GLH possessing glycyrrhizin (GL) and glycyrrhetic acid mono-glucuronide (GAMG) β-D-glucuronidases, Ruminococcus sp. PO1-3 possessing GL and GAMG β-D-glucuronidases and 3β-hydroxysteroid dehydrogenase and these mixed bacteria were cultured in GAM medium with and without GL, GAMG or both. GL added to Eubacterium sp. GLH accelerated the peaks of enhanced GL β-D-glucuronidase activity and suppressed GAMG β-D-glucuronidase activity, and GAMG delayed the peaks of the enhanced growth with GL and GAMG β-D-glucuronidase activities. GL added to Ruminococcus sp. PO1-3 enhanced gradually the growth with GL and GAMG β-D-glucuronidase activities, and GAMG enhanced slowly GL β-D-glucuronidase activity and rapidly the growth with GAMG β-D-glucuronidase activity. The metabolite glycyrrhetic acid (GA) was produced by Eubacterium sp. GLH and Ruminococcus sp. PO1-3 in larger amounts and faster from GAMG than from GL.GL(1.0 mM) and 1.0 mM GAMG added to these mixed bacteria enhanced the growth with GL and GAMG β-D-glucuronidase activities and were metabolized almost completely to GA in culture of 2 d and 1 d, respectively. It was found that the metabolism of GAMG was faster than that of GL.GL with GAMG added to mixed Eubacterium sp. GLH and Ruminococcus sp. PO1-3 cultured for 0 and 1 d led to a lower level of these enzyme activities and the consumption of GAMG more quickly, not GL. Low GAMG β-D-glucuronidase had the ability to hydrolyze GAMG well.