Potent Probiotic Yeast <i>Saccharomyces cerevisiae</i> TBRC 3616: Production Development for Food and Feed Applications

The global demand for probiotics has been increasing over the past few decades. Of these, <i>Saccharomyces cerevisiae</i> has attracted growing interest for use in functional foods and feed supplements due to its probiotic potential, nutritional value, and well-documented safety. For industrial applications, functional characterization, safety assessment, and robust production processes are key prerequisites. This study evaluated the probiotic properties and production potential of the <i>S. cerevisiae</i> strain TBRC 3616, isolated from decaying leaves in a tropical ecosystem in Thailand. The strain exhibited key probiotic traits, including acid and bile salt tolerance, Caco-2 cell adhesion, antipathogen activity, antioxidant capacity, and enzyme activities (catalase, protease, and esterase). The yeast exhibited no hemolytic activity and was not susceptible to the tested antibiotics, except colistin at 50 μg. High-cell-density cultivation was achieved using the developed fed-batch fermentation, resulting in a high yeast titer of 12.14 ± 0.03 log CFU L^-1, and a cell production rate of 10.52 ± 0.02 log CFU L^-1 h^-1. Furthermore, downstream processing efficiency was markedly enhanced by implementing an optimized freeze-drying protocol using 5% (w/v) maltodextrin, resulting in a 4-fold increase in cell viability compared to the control. These findings provide a production framework that supports the potential for scale-up of <i>S. cerevisiae</i> TBRC 3616 as a probiotic yeast for future applications.