Objective Hexavalent chromium (Cr(VI)) is an internationally recognized carcinogenic metal pollutant. Its effectively removing is crucial for ensuring ecological security and human health. Microbial remediation is economical and eco-friendly but its efficiency is limited by the single microbial removal mechanism and low environmental adaptability. Therefore, the construction of genetically engineered strains with composite removal ability and excellent environmental adaptability has emerged as a solution to address this limitation. Methods This study overcame the limitations of single-host systems by employing genetic engineering techniques to express the Cr(VI) removal functional fragment ChrA in Escherichia coli (E.coil) BL21 and Saccharomyces cerevisiae (S. cerevisiae) INVSC1. The Cr(VI) tolerance and removal capacity of engineered strains were systematically evaluated, and the removal mechanisms were preliminarily investigated using characterization assays. High-performing genetically engineered strains with enhanced Cr(VI) removal efficiency were screened, and their remediation performance was further examined and compared in sewage culture media with varying nutrient ratios. Result Both the engineered E. coli and S. cerevisiae strains possess biosorption and bioreduction capabilities, and exhibit superior Cr(VI) tolerance and removal efficiency compared to the wild-type strains. Compared to engineered E. coli strain, engineered S. cerevisiae strain exhibits stronger Cr(VI) tolerance and removal capabilities. Within 72 hours, the removal rate of 400 mg/L Cr(VI) by engineered S. cerevisiae strain is approximately twice that of engineered E. coli strain. Engineered S. cerevisiae strain demonstrate superior stability and tolerance in real-world sewage. Under the highest nutritional level (100%) support, engineered S. cerevisiae strain can completely remove 50 mg/L of Cr(VI) in actual industrial sewage within 24 hours. Conclusion Compared with E.coil BL21, S. cerevisiae INVSC1 is the optimal host strain for expressing Cr(VI) functional genes. The composite function of reduction and adsorption exhibited by engineered S. cerevisiae strain is more efficient in Cr(VI) removal, demonstrating significant potential for application.

Hexavalent Chromium, Microbial Remediation, Genetic Engineering, Industrial Sewage