3 Biotech. 2026 Aug;16(8):320. doi: 10.1007/s13205-026-04953-2. Epub 2026 Jul 9.
ABSTRACT
The complex and refractory structure of printed circuit boards (PCBs) limits the efficiency of conventional metal recovery processes. This led to the hypothesis that indigenous bacterial strains isolated from e-waste-contaminated sites may possess metabolic adaptations that facilitate metal mobilization. This study aims to isolate heavy-metal tolerant bacterial strains from e-waste contaminated soil, these isolates were evaluated for bioleaching efficiencies against PCBs at various pulp densities of 5 g/L, 10 g/L and 15 g/L, from which, Bacillus sp. SSNBT005 (Accession no: – PV453749), was found to be the most potent isolate. To ensure analytical rigor, experiments were performed in triplicate (n = 3) and were compared against abiotic controls to quantify the microbe mediated leaching. Statistical analysis (ANOVA, p < 0.05), confirmed that SSNBT005 significantly enhanced metal recovery, specifically, the strain achieved metal recovery efficiencies of about 94.24 ± 1.00, for silver (Ag) and upto 90.78 ± 0.37 for chromium (Cr), reaching raw recovery concentrations of 0.0186 g/L and 0.544 g/L respectively. FESEM analysis supports these quantitative findings, revealing some localized pitting and surface degradation of the PCB matrix as the result of microbial activity. FTIR analysis indicated changes in absorption bands associated with surface functional groups after bioleaching. These results support the hypothesis that SNBT005 actively facilitates metal recovery.
SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-026-04953-2.
PMID:42434791 | PMC:PMC13350597 | DOI:10.1007/s13205-026-04953-2
