Role of oxygen supply in α, ω‐dodecanedioic acid biosynthesis from n‐dodecane by Candida viswanathii ipe‐1: Effect of stirring speed and aeration

Abstract

α, ω‐Dodecanedioic acid (DC12) usually serves as a monomer of polyamides or some special nylons. During the biosynthesis, oxygenation cascaded in conversion of hydrophobic n‐dodecane to DC12, while the oxidation of n‐dodecane took place in the intracellular space. Therefore, it was important to investigate the role of oxygen supply on the cell growth and DC12 biosynthesis. It was found that stirring speed and aeration influenced the dissolved oxygen (DO) concentration which in turn affected cell growth as well as DC12 biosynthesis. However, the effect of culture redox potential (Orp) level on DC12 biosynthesis was more significant than that of DO level. For DC12 biosynthesis, the first step was to form the emulsion droplets through the interaction of n‐dodecane and the cell. When the stirring speed was enhanced, slits in the surface layer of the emulsion droplets would be increased. Thus, the substances transportation by water through the slits would be intensified, leading to an enhanced DC12 production. Compared with the batch culture at a lower stirring speed (400 rpm) without culture redox potential (Orp) control, the DC12 concentration was increased by 5 times up to 201.3 g/L with Orp controlled above 0 mV at a higher stirring speed (800 rpm).

Advances in bio‐based production of dicarboxylic acids longer than C4

“…Typically, an exogenously applied fatty acid is imported and oxidized by P450 monooxygenase to the corresponding ω-hydroxy fatty acid. Several yeasts, such as Candida tropicalis, Candida sorbophila or Yarrowia lipolytica were reported to produce DCAs at industrially relevant levels by converting the corresponding fatty acids or alkanes [13][14][15][16]. When alkanes are used as substrates, they are initially converted to fatty acids with three oxidative reactions at the α position and the resulting fatty acids were further converted into DCAs via ω-oxidation [5].…”

“…Limited oxygen supply for higher level of reductive driving force Reversal-βoxidation [19,42] 3. Optimization of stirring speed and aeration ω-Oxidation [16] …”

“…When alkanes are used as substrates, they are initially converted to fatty acids with three oxidative reactions at the α position and the resulting fatty acids were further converted into DCAs via ω-oxidation [5]. Several yeasts, such as Candida tropicalis, Candida sorbophila or Yarrowia lipolytica were reported to produce DCAs at industrially relevant levels by converting the corresponding fatty acids or alkanes [13][14][15][16]. For example, engineered strains of C. tropicalis by amplifying the copies of P450 genes and blocking β-oxidation either partially or completely produced up to 50 g/L C6 DCA, 140 g/L C12 DCA, 210 g/L C14 DCA or 100 g/L C18 DCA from fatty acids or alkanes [15,17].…”

“…Oxygen supply is one of the most important factors during fermentation [16,74]. As for the synthetic pathways of producing DCAs, several reactions require oxygen to participate in (e.g.…”