Inorganic phosphate enhances growth and cadmium tolerance in a newly isolated Candida tropicalis

Abstract

Cadmium contamination in soil, water and biota impacts human health and ecosystems. Since conventional treatments are often inefficient, biosorption using microorganisms has been explored as a promising approach. This study investigates the role of inorganic phosphate (KH2PO4) in alleviating cadmium stress and enhancing cadmium accumulation in a newly isolated strain of Candida tropicalis NUTI–P8. Cell viability assays were performed under cadmium chloride (CdCl2) concentrations (900 and 1,000 µM) with phosphate supplementation (50 and 100 mM). The results show that exposure to CdCl2 markedly reduced the growth of C. tropicalis NUTI–P8 (∼2-fold reduction), whereas supplementation with 100 mM KH2PO4 significantly enhanced growth performance (∼5-fold), cell viability (∼3-fold) and enzymatic activity (∼7-fold) under 1,000 µM CdCl2 stress. Moreover, cadmium accumulation increased from 116.90 ± 1.02 µM (1,000 µM CdCl2) to 188.89 ± 18.12 µM with phosphate supplementation (100 mM KH2PO4). The findings demonstrate that inorganic phosphate enhances growth and cadmium tolerance in C. tropicalis NUTI–P8, and further highlight the potential of this new yeast isolate as a bioresource for mitigating cadmium contamination, providing insights into phosphate-mediated alleviation of heavy metal stress.