Combining Different Yarrowia divulgata Yeast-Based Fermentations into an Integrated Bioprocess for Manufacturing Pigment, Sweetener, Bioemulsifier, and Skin Moisturiser

In this study, we examined the enhancement of erythritol production by the Yarrowia divulgata strain 1485. Although erythritol fermentation has been thoroughly investigated in earlier studies, the influence of inoculum ratio has not been comprehensively addressed. Therefore, this parameter was selected as the focus of the present work. Since industrial-scale erythritol production is typically carried out using more efficient fungal strains, further improvements in economic viability are primarily expected through integration with other biotechnological processes, allowing the simultaneous generation of multiple valuable products. To this end, the erythritol fermentation was coupled with microbial pigment production, and the potential recovery of additional compounds—such as biodetergents and cosmetic ingredients—were also explored. Based on the results, the fermentation with a 15% inoculation rate appears to be the most effective, producing 67.9 ± 6.0 g/L of erythritol, and 61.81 ± 0.02 mg/L of pigment was successfully extracted at the end of the pigment fermentation. The cells seem capable of increasing the skin’s moisturizing effect according to our preliminary tests when glass bead cell disruption is used, and the emulsifier has also proven to be effective, maintaining an emulsification index (EI) above 50% even after 24 h. When performing a kinetic model, we found that the measured data matched the model predictions and confirmed optimal inoculation size (15%), providing a solid basis for subsequent techno-economic analysis. The integration of the two basic fermentations (erythritol and pigment) is therefore considered successful, and the Yarrowia divulgata strain appears to have great biotechnological potential.