Multivariate optimization of multimetal biosorption by a microbial consortium: insights from bacterial community analysis

Metal contamination in aquatic environments requires efficient and environmentally sustainable remediation strategies. This study aimed to optimize the simultaneous biosorption of Cu, Pb, Zn, Cd, and Ni in aqueous solutions using a mixed microbial consortium through a multivariate factorial experimental design. The evaluated parameters included pH, contact time, initial multielement metal concentration, microbial cell density, and a multiple response index. The results demonstrated that pH and initial metal concentration were the most influential variables affecting biosorption efficiency, achieving removal rates above 80% for all evaluated metals. Although the consortium was composed of bacteria and fungi, community-level analyses were restricted to the bacterial fraction. Integrated microbiological data suggested complementary functional roles within the consortium, with the genus Bacillus contributing centrally to metal biosorption, while Pseudomonas played a supportive role, possibly associated with metal stress tolerance and system stability. Overall, the findings highlight the strong potential of this microbial consortium as a sustainable and low-cost biosorbent for the treatment of metal-contaminated effluents.