Development of a zinc-enriched yeast strain for nutritional applications using low-cost ingredients

Zinc plays a vital role in many bodily functions, yet zinc deficiency remains a major global health issue. This study reports enriching a newly isolated yeast strain, Candida sp. pz46, with zinc and optimizing its biomass production on cost-effective substrates. Out of 50 yeast isolates tested, Candida sp. pz46 showed the highest zinc tolerance (up to 1 g/L) and accumulated about 700 mg Zn per g of dry biomass. Biomass yield was optimized using response surface methodology (Box-Behnken design), reaching 14.49 g/L with sugarcane molasses and corn steep liquor (CSL) as substrates. Comparison with Saccharomyces cerevisiae confirmed that Candida sp. pz46 had better growth and zinc accumulation. Simulated gastric and intestinal digestion tests showed that over 77% of intracellular zinc was released within 4 h, while cytotoxicity testing (MTT assay) confirmed the non-toxic nature of the enriched biomass toward HUVEC cells. Overall, these results suggest Candida sp. pz46 could be a candidate for industrial-scale production of zinc-enriched yeast using sustainable substrates, providing an effective nutritional strategy to address zinc deficiency.