Lead-Resistant Bacteria from Contaminated Terrestrial Environments: A Systematic Review of Isolation, Characterization, and Bioremediation Potential

Abstract

Lead (Pb) is a persistent, non-biodegradable pollutant that accumulates in soils and enters food chains, threatening ecosystems and human health. Indigenous bacteria from lead-polluted sites have evolved ways of tolerating and detoxifying the metal, making them attractive agents for sustainable remediation. We conducted a systematic review following PRISMA 2020 guidelines to synthesize empirical studies published between January 2023 and June 2026 on the isolation, characterization, and bioremediation potential of lead-resistant bacteria. Scopus, Web of Science, PubMed, ScienceDirect, and Google Scholar were searched, and 20 of 612 records met the inclusion criteria. Fifteen studies were from Asia, four from Nigeria, and one from Chile. Bacillus was the most frequently named genus, followed by Pseudomonas, Kocuria, Mesobacillus, Sphingobium, and Lysinibacillus. Lead tolerance and removal were attributed to biosorption, intracellular bioaccumulation, biomineralization, extracellular sequestration, biosurfactant production, antioxidative defence, and active efflux. Thirteen studies relied on morphological and biochemical identification alone, whereas seven reported molecular characterization, including 16S rRNA gene sequencing. Almost all work was laboratory-based, and field validation was largely absent. Indigenous lead-resistant bacteria, particularly Bacillus and Pseudomonas, are promising candidates for lead remediation, but the evidence is limited by non-standardized methods, thin molecular characterization, geographic imbalance, and a lack of field trials. Future work should prioritize standardized reporting, routine genome-based identification, biosafety screening, microbial consortia, and field-scale studies in under-represented regions such as Africa