Effect of Metabolic Regulators and Aeration on Isocitric Acid Synthesis by Yarrowia lipolytica Grown on Ester-Aldehyde Fraction

Abstract

Isocitric acid (ICA) has found wide application in medicine as a promising compound with powerful antioxidant activity to combat oxidative stress. In the known microbiological processes of ICA production by non-conventional yeast Yarrowia lipolytica, the pure carbon sources are commonly used. ICA can be also synthetized by Y. lipolytica from ester-aldehyde fraction (EAF)-waste of the ethanol production process. A highly effective method of ICA production from EAF based on regulation of key enzymes (aconitate hydratase and isocitrate lyase) by metabolic regulators (iron and itaconic acid) and aeration was developed. It is recommended to cultivate Y. lipolytica VKM Y-2373 under nitrogen deficiency conditions, a high aeration (60% of air saturation), an addition of 15 mM itaconic acid, and 2.4 mg/L iron. Under optimal conditions, Y. lipolytica VKM Y-2373 produced 83 g/L ICA with isocitrate to citrate ratio of 4.1:1 and mass yield of 1.1 g/g. The putative mechanism of ICA overproduction from EAF by Y. lipolytica was suggested.

Modelling of the Citric Acid Production from Crude Glycerol by Wild-Type Yarrowia lipolytica DSM 8218 Using Response Surface Methodology (RSM)

“…The concentration of dissolved oxygen (DO) is an important parameter to take in account for the CA production [ 38 ] and generally for the production of organic acids such as isocitric acid [ 15 , 39 ], pyruvic acid [ 40 ] and α-Ketoglutaric Acid [ 41 ]. Ferreira et al [ 42 ] showed that raising the oxygen volumetric mass transfer coefficient (Kla), the conversion of crude glycerol by Y. lipolytica W29 to CA increased of 700%.…”

Large-Scale Production of Isocitric Acid Using Yarrowia lipolytica Yeast with Further Down-Stream Purification

“…Usually, the stirrer rates of 200–1000 rpm and air flow rate within the range of 0.24–2.0 vvm generate the pO 2 values of 30–60% saturation, which favored the synthesis of high-value metabolites in Y. lipolytica [ 26 , 28 , 34 , 35 ]. We observed that a rise in pO 2 value from 5 to 60% saturation enhanced ICA production by 3.3 times in Y. lipolytica grown on ester-aldehyde fraction in small fermenters [ 25 ]. In addition, we found that, in Y. lipolytica cultivated at a pO 2 of 50–55% saturation, the yield of ICA from rapeseed oil (Y p ) and the specific rate of ICA synthesis (q p ) were much higher than the values found in the cultures with oxygen deficiency (5–10% saturation) [ 13 ].…”

“…The literature data describe the processes of ICA production from ethanol [ 11 , 12 ], rapeseed oil [ 13 , 14 , 15 ], sunflower oil [ 16 , 17 , 18 , 19 ], glucose [ 20 ], glycerol [ 20 ], raw glycerol [ 21 , 22 , 23 ], and ethanol industry waste [ 24 , 25 ]. The above articles note that Y. lipolytica has the ability to synthesize ICA and citric acid (CA) simultaneously in a proportion that depends on the strain, carbon source, and composition of the growth medium.…”

“…The ratio between citric acids toward the ICA production can be shifted via the inhibition of isocitrate lyase (ICL), catalyzing the cleavage of isocitrate to succinate and glyoxylate in the glyoxylate cycle. We reported that the use of the ICL inhibitors such as oxalic and itaconic acids is a simple and convenient method of predominant ICA synthesis from different carbon sources [ 12 , 13 , 14 , 17 , 25 ]. On the contrary, the transformant Y. lipolytica , with overexpression of the gene ICL1 , mainly accumulated CA [ 18 ].…”

“…It should be noted that most of the reported studies have been carried out in lab-scale fermenters with volumes ranging from 600 mL to 10 L [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]; however, there have been no reports of ICA production in pilot-scale bioreactors. There are only a few articles that cover large-scale processes using Y. lipolytica , namely, lipase production [ 29 , 30 ].…”