| Autor: |
Meesschaert, Boudewijn, Moons, Nico, Steurs, Gert, Monballiu, Annick, Amery, Ruis, Jooken, Etienne, Geuns, Jan |
| Zdroj: |
Journal of Environmental Chemical Engineering; December 2021, Vol. 9 Issue: 6 |
| Abstrakt: |
Steviol glycosides are fully deglycosylated to steviol in the presence of bacterial populations that were isolated from different soil samples. Heating (20 min at 80 °C) or boiling (10 min at 100 °C) of soils had little effect on the steviol formation. It is suggested that bacteria that survived with highly resistant spores are responsible for the deglycosylation of steviol glycosides. A bio-organic preparation method for steviol was developed which had a total yield of 90%. Beside deglycosylation, other reactions also occur. The steviol formed can be degraded. Under anaerobic conditions, rebaudioside A was not hydrolyzed while stevioside was degraded to steviol viarubusoside. Moreover, after an extended incubation (4 weeks) and repetitive sub-cultivation, a bacterial community was selected that converted steviol glycosides to a new and unknown ketone, given the nickname Monicanone. It appeared to be the steviol nucleus without the A-ring that underwent a Walden inversion at its original C-10. A second and related unknown compound could be isolated from an impure preparation of Monicanone by chromatographic separation and purification; this compound was a reduced form of Monicanone and named Monicanol. Steviol glycosides that were incubated with a UASB effluent of an industrial wastewater treatment system – supplemented or not – with sludge of a lab scale nitrification or denitrification unit – were completely degraded viasteviol and Monicanone. |
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