Whole-Cells of Yarrowia lipolytica Applied in “One Pot” Indolizine Biosynthesis

Abstract

A series of yeast strains was tested in order to evaluate their catalytic potential in biocatalysis of one-pot indolizine’s synthesis. Yeast cultivation was performed in a submerged system at 28 °C for 72 h at 180 rpm. An assessment of the reagents’ toxicity on yeast viability and metabolic functionality concluded that the growth potential of three Yarrowia lipolytica strains were least affected by the reactants compared to the other yeast strains. Further, crude fermentation products (biomass and cell-free supernatant)—obtained by submerged cultivation of these yeasts—were used in multistep cascade reactions for the production of fluorescent indolizine compounds with important biologic activities. A whole–cell catalyzed multicomponent reaction of activated alkynes, α-bromo-carbonyl reagents and 4,4′-bipyridine, at room temperature in buffer solution led to the efficient synthesis of bis-indolizines 4a, 4b and 4c, in good-to-excellent yields (47%–77%). The metabolites of the selected Y. lipolytica strains can be considered effective biocatalysts in cycloaddition reactions and the high purity and bioconversion yields of the synthesized indolizines indicates a great potential of this type of “green” catalysts. Seeds of Triticum estivum L. were used to investigate the impact of the final products on the germination and seedling growth. The most sensitive physiological parameters suggest that indolizines, at the concentrations tested, have non-toxic effect on germination and seedling growth of wheat, fact also confirmed by confocal laser scanning microscopy images.

Yarrowia lipolytica Yeast: A Treasure Trove of Enzymes for Biocatalytic Applications—A Review

“…Botezatu et al [31] investigated the ability of different yeast strains to catalyze the synthesis of indolizine derivatives. The compounds of interest possess heterocyclic ring cores and may exhibit precious biological activities.…”

“…At the same time, the application of biomass revealed that it can be used as a biocatalyst, but its reactions were weaker than the supernatant. Furthermore, the presence of methoxyl or nitro substituents impacted the final yields of bis-indolizines, which were about 50% [31]. On the other hand, Zieniuk et al [32] investigated freeze-dried Y. lipolytica biomass and freeze-dried supernatant in ethyl hydrocinnamate synthesis.…”

“…Figure2. "One-pot″ bis-indolizines biosynthesis with the use of Y. lipolytica biomass or cell-free supernatant[31]. R = H, OCH3, or NO2.…”

Biocatalytic Process Optimization

“…Indolizines have been synthesized by lipases from Candida antarctica [18]. Botezatu et al [19] used whole cells to catalyze a multicomponent reaction of activated alkynes, α-bromo-carbonyl reagents and 4,4 -bipyridine in the synthesis of bis-indolizines. Several yeast strains were tested to evaluate the effect of the reactants on their physiological activity.…”