Production of selenium enriched saccharomyces boulardii in pilot scale bioreactor

Abstract

Selenium (Se) yeast has been widely used as a Se supplementation for humans. Supplementation with Se-enriched yeast in animal and human diet has been proven to have beneficial health effects. One major disadvantage in Se yeast production is the complexity in the yeast production. The objective of this study is to optimize cell mass production of Saccharomyces boulardii for Selenium enrichment process. Production of S. boulardii cell mass was optimized by using both classical and statistical approach. Production of high cell mass of S. boulardii was upscaled using a 16-L stirred tanked bioreactor in batch and fed-batch cultivation strategies where the fed batch bioreactor cultivation with complete medium showed the highest cell mass production at 34.16 g L- 1. During Se enrichment process, effects of different Se concentration and addition time were examined to maximize the Se absorption process by S. boulardii. The production of Se yeast was further upscaled in a 16-L stirred tank bioreactor in batch and fed batch cultivation strategies. In Se enrichment process 90 mg mL-1 Se which added at 16 hour of cultivation time for 24 hour was found to be best condition for Se enrichment in S. boulardii. The process was used in fed-batch cultivation in 16-L stirred tank bioreactor with full medium. Maximum cell biomass was at 24.97 g L-1 with 0.177 h-1 specific growth rate. The highest Se content was achieved at 41.65 µg g -1 with 1.78 µg g-1 h-1 absorption rate. Therefore it can concluded that addition of Se in late exponential phase of S. boulardii growth is the most suitable condition to minimize the inhibition effect on S. boulardii cell mass production and at the same time maximize the absorption of Se process.