Whole-cell bioconversion of naringenin to high added value hydroxylated compounds using Yarrowia lipolytica 2.2ab in surface and liquid cultures

Enhanced Antioxidant, Antifungal, and Herbicidal Activities through Bioconversion of Diosgenin by Yarrowia lipolytica P01a

This study explores the bioconversion of diosgenin by Yarrowia lipolytica P01a, focusing on enhancing the antioxidant, antifungal, and herbicidal activities of the resulting extracts. The bioconversion process, involving glycosylation and hydroxylation, produced significant amounts of protodioscin and soyasaponin I. The extracts showed superior antioxidant activity, with up to 97.02% inhibition of ABTS· radicals and 33.30% inhibition of DPPH· radicals at 1000 mg L-1 of diosgenin. Antifungal assays revealed strong inhibitory effects against Botrytis cinerea, Alternaria sp., and Aspergillus niger, with maximum inhibition rates of 67.34%, 35.63%, and 65.53%, respectively. Additionally, the herbicidal activity of the bioconverted extracts was comparable to commercial herbicides, achieving 100% inhibition of seed germination in both monocotyledonous and dicotyledonous plants. These findings suggest that the Y. lipolytica P01a-mediated bioconversion of diosgenin could provide a sustainable and eco-friendly alternative for developing natural biofungicides and bioherbicides.

Novel flavonoid C-8 hydroxylase from Rhodotorula glutinis: identification, characterization and substrate scope

Background

The regioselective hydroxylation of phenolic compounds, especially flavonoids, is still a bottleneck of classical organic chemistry that could be solved using enzymes with high activity and specificity. Yeast Rhodotorula glutinis KCh735 in known to catalyze the C-8 hydroxylation of flavones and flavanones. The enzyme F8H (flavonoid C8-hydroxylase) is involved in the reaction, but the specific gene has not yet been identified. In this work, we present identification, heterologous expression and characterization of the first F8H ortho-hydroxylase from yeast.

Results

Differential transcriptome analysis and homology to bacterial monooxygenases, including also a FAD-dependent motif and a GD motif characteristic for flavin-dependent monooxygenases, provided a set of coding sequences among which RgF8H was identified. Phylogenetic analysis suggests that RgF8H is a member of the flavin monooxygenase group active on flavonoid substrates. Analysis of recombinant protein showed that the enzyme catalyzes the C8-hydroxylation of naringenin, hesperetin, eriodyctiol, pinocembrin, apigenin, luteolin, chrysin, diosmetin and 7,4ʹ-dihydroxyflavone. The presence of the C7-OH group is necessary for enzymatic activity indicating ortho-hydroxylation mechanism. The enzyme requires the NADPH coenzyme for regeneration prosthetic group, displays very low hydroxyperoxyflavin decupling rate, and addition of FAD significantly increases its activity.

Conclusions

This study presents identification of the first yeast hydroxylase responsible for regioselective C8-hydroxylation of flavonoids (F8H). The enzyme was biochemically characterized and applied in in vitro cascade with Bacillus megaterium glucose dehydrogenase reactions. High in vivo activity in Escherichia coli enable further synthetic biology application towards production of rare highly antioxidant compounds.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-022-01899-x.