Heterologous overexpression of bacterial hemoglobin VHb improves erythritol biosynthesis by yeast Yarrowia lipolytica

Abstract

Background Yarrowia lipolytica is an unconventional yeast with a huge industrial potential. Despite many advantages for biotechnological applications, it possesses enormous demand for oxygen, which is a bottleneck in large scale production. In this study a codon optimized bacterial hemoglobin from Vitreoscilla stercoraria (VHb) was overexpressed in Y. lipolytica for efficient growth and erythritol synthesis from glycerol in low-oxygen conditions. Erythritol is a natural sweetener produced by Y. lipolytica under high osmotic pressure and at low pH, and this process requires high oxygen demand. Results Under these conditions the VHb overexpressing strain showed mostly yeast-type cells resulting in 83% higher erythritol titer in shake-flask experiments. During a bioreactor study the engineered strain showed higher erythritol productivity (QERY = 0.38 g/l h) and yield (YERY = 0.37 g/g) in comparison to the control strain (QERY = 0.30 g/l h, YERY = 0.29 g/g). Moreover, low stirring during the fermentation process resulted in modest foam formation. Conclusions This study showed that overexpression of VHb in Y. lipolytica allows for dynamic growth and efficient production of a value-added product from a low-value substrate.

Rye and Oat Agricultural Wastes as Substrate Candidates for Biomass Production of the Non-Conventional Yeast Yarrowia lipolytica

“…In contrast to the previous experiment, Y. lipolytica was grown in a larger volume, and oxygen supply in the medium was better. Previously, it was shown that providing a high level of dissolved oxygen is crucial for efficient growth of Y. lipolytica [36]. The fermentation process took 120 h, and the obtained results of biomass production are shown in Figure 3 and Table 2.…”

Impact of oxygen availability on heterologous geneexpression and polypeptide secretion dynamics in Yarrowia lipolytica‐based protein production platforms

“…Because the OTR decreases as the scale of the bioreactor increases, oxygen availability (OA) is a parameter difficult to master in bioreactor especially at large scale. Apart from classical modulation of impellers stirring speed and air flow inlet, this challenge has been addressed in many different bioprocessing and genetic engineering solutions (Mirończuk et al, 2019; Vandermies & Fickers, 2019). For example, increasing bioreactor pressure or utilization of perfluorodecalin as a second liquid phase result in an increase of OTR and thus of OA (Amaral et al, 2008; Lopes, Gomes, Mota, & Belo, 2009).…”

“…In another strategy, the increase in the cell's oxygen uptake rate was achieved by overexpression of VHb gene from Vitreoscilla , encoding a haemoglobin‐like protein. In Y. lipolytica , this has led to an improved cell growth capacity (Bhave & Chattoo, 2003) but also to higher productions of intracellular lipids (Zhang et al, 2019) or erythritol (Mirończuk et al, 2019).…”

Yarrowia lipolytica as an Oleaginous Platform for the Production of Value-Added Fatty Acid-Based Bioproducts

“…Previously, researchers have showed that the heterologous expression of gene encoding the bacterial hemoglobin from Vitreoscilla stercoraria (VHb) can improve the oxygen utilization efficiency and further increase the productivity (Suen et al, 2014;Zhang et al, 2017). Recently, Mirończuk et al (2019) performed that the improved erythritol synthesis is obtained in Y. lipolytica, by overexpressing the codon-optimized bacterial hemoglobin (VHb). Through improving oxygen transfer rate using higher agitation rates or pure oxygen for aeration, the production of γ-decalactone was successfully enhanced (Moradi et al, 2013).…”