HOG-Independent Osmoprotection by Erythritol in Yeast Yarrowia lipolytica

Abstract

Erythritol is a polyol produced by Yarrowia lipolytica under hyperosmotic stress. In this study, the osmo-sensitive strain Y. lipolytica yl-hog1Δ was subjected to stress, triggered by a high concentration of carbon sources. The strain thrived on 0.75 M erythritol medium, while the same concentrations of glucose and glycerol proved to be lethal. The addition of 0.1 M erythritol to the medium containing 0.75 M glucose or glycerol allowed the growth of yl-hog1Δ. Supplementation with other potential osmolytes such as mannitol or L-proline did not have a similar effect. To examine whether the osmoprotective effect might be related to erythritol accumulation, we deleted two genes involved in erythritol utilization, the transcription factor Euf1 and the enzyme erythritol dehydrogenase Eyd1. The strain eyd1Δ yl hog1Δ, which lacked the erythritol utilization enzyme, reacted to the erythritol supplementation significantly better than yl-hog1Δ. On the other hand, the strain euf1Δ yl-hog1Δ became insensitive to supplementation, and the addition of erythritol could no longer improve the growth of this strain in hyperosmotic conditions. This indicates that Euf1 regulates additional, still unknown genes involved in erythritol metabolism.

Overexpression of YALI0B07117g Encoding Erythrose Reductase Homolog Results in Enhanced Erythritol Synthesis From Glycerol by the Yeast Yarrowia Lipolytica.

“…The yeast Y. lipolytica is able to synthesize erythritol from glycerol, as a response to high osmotic stress [4]. It was shown that the last step of the erythritol synthesis pathway is reduction of d-erythrose to erythritol (Figure 1).…”

“…Erythritol is a four-carbon polyol that can be found in fruits, such as pears, grapes or melon, where it acts as a carbon store, while many microorganisms produce erythritol under high osmotic pressure as an osmoprotectant [4]. It is characterized by stability at high temperatures and over a wide range of pH [5].…”

Transcriptomic Analysis of the Erythritol High-Yielding Mutant Strain Yarrowia lipolytica Y44

“…yeasts, such as Zygosaccharomyces, Debaryomyces, Hansenula, Pichia, can grow under high osmotic pressure (high sugar content or salinity) (Brown, 1978). These hyperosmolar yeasts can stimulate an osmotic response mechanism in a hyperosmolar environment, that is, accumulate one or more compatible solutes for resistance to hyperosmolar environment (Rzechonek et al, 2020;Libo, 2015). Glycerol is the most common osmoprotective agent in yeast, but sugar alcohols such as erythritol, D-arabitol and mannitol also have similar functions (Rzechonek et al, 2020;Libo, 2015).…”

The Overexpression of YALI0B07117g Results in Enhanced Erythritol Synthesis from Glycerol by the Yeast Yarrowia lipolytica

“…Erythritol is a four-carbon polyol found in fruit such as pears, grapes or melons where it acts as a carbon store. Many microorganisms produce erythritol under high osmotic pressure as an osmoprotectant [4]. It is characterized by stability at high temperatures and over a wide range of pH values [5].…”

“…The yeast Y. lipolytica is able to synthesize erythritol from glycerol as a response to high osmotic stress [4]. It was shown that the last step of the erythritol synthesis pathway is the reduction of d-erythrose to erythritol (Figure 1).…”