Introduction:
Microbial-mediated bioremediation offers a sustainable solution for detoxifying polluted environments, but its molecular mechanisms remain poorly understood. Recent advances in multi-omics approaches, particularly transcriptomics, proteomics, and metabolomics, have enabled detailed insight into cellular responses to environmental stressors. In this study, a mass spectrometry-based quantitative proteomic profiling approach was applied to investigate alterations in protein expression in Paramecium multimicronucleatum exposed to cadmium (Cd²⁺), a toxic heavy metal known to cause cellular stress.

Methods:
A mass spectrometry-based quantitative proteomic approach was applied to analyze protein abundance changes in P. multimicronucleatum after Cd²⁺ exposure as compared to a control. Samples were processed using the Proteome Discoverer software to identify and quantify peptide spectral matches, total peptides, and proteins. Differential abundance was determined using statistical analysis (p ≤ 0.05).

Results:
The proteomic analysis identified 7,416 peptide spectral matches, corresponding to 2,824 unique peptides and 989 proteins. Among these, 29 proteins showed statistically significant differential abundance in cadmium-treated samples. Six proteins were upregulated, while twenty-three were downregulated. These proteins were functionally linked to stress responses, energy metabolism, protein degradation, cell growth, and hormone processing.

Conclusions:
This comprehensive comparative proteomic analysis provides valuable insights into the molecular adaptations of Paramecium under cadmium stress. The findings contribute to our understanding of metal detoxification pathways, supporting future studies on bioremediation strategies for environmental sustainability.