Kinetic modeling and optimization of ethanol fermentation by the marine yeast Wickerhamomyces subpelliculosus ZE75

The study aims to enhance ethanol production by Wickerhamomyces subpelliculosus ZE75 isolated from marine sediment. In addition, analyzing the kinetic parameters of ethanol production and optimization of the fermentation conditions was performed. The marine yeast isolate ZE75 was selected as the front runner ethanol-producer, with an ethanol yield of 89.77 gL⁻¹. ZE75 was identified relying on the phenotypic and genotypic characteristics of W. subpelliculosus. The genotypic characterization based on the Internal Transcribed Spacer (ITS) sequence was deposited in the GenBank database with the accession number OP715873. The maximum specific ethanol production rate (v_max) was 0.482 gg⁻¹ h⁻¹ at 175 gL⁻¹ glucose concentration, with a high accuracy of R² 0.95. The maximum growth specific rates (μ_max) were 0.141 h⁻¹ obtained at 150 gL⁻¹ glucose concentration with R² 0.91. Optimization of the fermentation parameters such as pH and salinity has been achieved. The highest ethanol yield 0.5637 gg⁻¹ was achieved in a 100% natural seawater-based medium. The maximum ethanol production of 104.04 gL⁻¹ was achieved at pH 4.5 with a specific ethanol rate of 0.1669 gg⁻¹ h⁻¹. The findings of the present study recommend the possibility of ethanol production from a seawater-based medium on a large scale using W. subpelliculosus ZE75.

Graphical abstract