Optimization of Squalene Production by Pseudozyma sp. P4-22

Abstract

Squalene is an important bioactive substance widely used in the food, pharmaceutical, and cosmetic industries. Microbial production of squalene has gained prominence in recent years due to its sustainability, safety, and environmental friendliness. In this study, a mutant strain, Pseudozyma sp. P4-22, with enhanced squalene-producing ability, was obtained through atmospheric and room temperature plasma mutagenesis of the previously screened squalene-producing yeast Pseudozyma sp. SD301. The P4-22 strain demonstrated the ability to produce squalene using various carbon and nitrogen sources. We optimized the culture conditions by employing cost-effective corn steep liquor as the nitrogen source, and the optimal pH and sea salt concentration of the medium were determined to be 5.5 and 5 g/L, respectively. Under optimal cultivation conditions, the biomass and squalene production reached 64.42 g/L and 2.06 g/L, respectively, in a 5 L fed-batch fermentation. This study highlights the potential of Pseudozyma sp. P4-22 as a promising strain for commercial-scale production of squalene.

Keywords: Pseudozyma sp.; corn steep liquor; culture optimization; fermentation; mutagenesis; squalene.

Figure 1

Squalene titer of selected strains obtained by ARTP mutagenesis. Different lowercase letters (a, b, c, d, e) above bars indicate statistically significant differences between means (p < 0.05), while shared letters denote no significant difference.

Figure 2

The optical image of Pseudozyma sp. P4-22 (A) and the gas chromatography spectrum of extracted lipid (B).

Figure 3

Effects of different corn steep liquor concentrations on growth and squalene production of P4-22. Different lowercase letters (a, b, c, d) above bars indicate statistically significant differences between means (p < 0.05), while shared letters denote no significant difference.

Figure 4

Effects of different initial pH on strain growth and accumulation of squalene. Different lowercase letters (a, b, c, d) above bars indicate statistically significant differences between means (p < 0.05), while shared letters denote no significant difference.

Figure 5

The growth and squalene accumulation of P4-22 at different salt concentrations. Different lowercase letters (a, b, c) above bars indicate statistically significant differences between means (p < 0.05), while shared letters denote no significant difference.

Figure 6

Fed-batch fermentations of Pseudozyma sp. P4-22 (A) and Pseudozyma sp. SD301 (B).