Selection of Zygosaccharomyces rouxii strains resistant to cadmium with improved removal abilities through ultraviolet-diethyl sulfate cooperative mutagenesis

Cd²⁺ resistance and bioaccumulation capacity were selected from parental Zygosaccharomyces rouxii (CRZ-0) while maintaining NaCl tolerance using protoplast mutagenesis technology. Ultraviolet-diethyl sulfate (UV-DES) cooperative mutagenesis, followed by preliminary screening and rescreening, was used to select the mutant strain CRZ-9. CRZ-9 grew better than CRZ-0 in YPD medium with 20 or 50 mg L⁻¹ of Cd²⁺. Scanning electron microscopy observations and flow cytometry tests indicated that CRZ-9 was more effective at eliminating reactive oxygen species (ROS) generated by Cd²⁺, which led to less cellular structural damage and lower lethality. Furthermore, compared with CRZ-0, CRZ-9 exhibited increased potential for application with higher Cd²⁺ removal ratio, wider working pH range, and lower biomass dosage in Cd²⁺ bioaccumulation. The mutant strain CRZ-9 possessed improved Cd²⁺ resistance and bioaccumulation capacity and therefore is a promising strain to remove Cd²⁺ from wastewater.