PRISMA-based review of Pseudomonas spp. in microbial heavy-metal bioremediation: mechanisms and taxonomy

<i>Bacillus</i> and <i>Pseudomonas</i> were the most frequently investigated genera, with <i>Bacillus</i> spp. achieving the highest removal efficiencies (>80%-90%) through biosorption and biomineralization mechanisms. On the other hand, <i>Pseudomonas</i> spp. showed a high functional and genetic versatility, combining efflux systems, enzymatic redox transformations, EPS production, and biofilm-mediated resilience, particularly in multi-metal and fluctuating environmental conditions. Median removal efficiencies was at least 70% in controlled laboratory assays, while it was 10%-25% in soil. Despite methodological heterogeneity, the evidence identifies <i>Pseudomonas</i> as a mechanistic benchmark genus rather than a universally superior biosorbent, owing to its extensive genomic characterization and broad detoxification repertoire. The review highlights the need for standardized experimental protocols, integration of multi-omics approaches, and field-scale validation to improve data comparability and to facilitate the translation of microbial bioremediation from laboratory studies to sustainable environmental applications.