Isolation of Cd Removal Bacteria from Beira Lake, Colombo, Sri Lanka and Evaluati on of their Capacity in Cadmium Removal

Cadmium (Cd), a heavy metal, is reported to be exceeding its consumable levels in the environment due to several anthropogenic activities. Cd contamination thus challenges the ecosystems and human health due to its persistence and toxicity. It is confirmed that bioaccumulation of Cd leads to cancers and osteoporosis. Hence, concerning their eco-friendliness and cost-effectiveness, urgent remediation methods are needed for clearing the issue of Cd-contaminated water and soil. The present study deals with three Cd-resistant bacterial strains isolated from Beira Lake, Sri Lanka; and named as TTCB, TTGB, and TTPB. The isolated strains are found to have performed remarkably effectively with the Cd removal efficiencies of 97.4%, 97.5%, and 97.5%, respectively, as determined by an atomic absorption spectrophotometric assay. Their highest effectiveness was found at temperatures ranging from 30°C to 40°C and in a pH range of 6 to 7. Moreover, the isolated strains indicated higher Minimal Inhibitory Concentrations (1200 – 2000 ppm), confirming a strong tolerance to Cd. It is highlighted that the MIC levels of the isolated strains are remarkable in comparison with the model organisms as Bacillus cereus ATCC 10876 and Pseudomonas aeruginosa ATCC (300 – 700 ppm). The resulting potentiality of the isolated strains has suggested a promising bioremediation application for Cd- contaminated environments, offering a valuable solution to address this pressing environmental issue. Keywords: Cadmium; Beira Lake; Anthropogenic activities; Bioaccumulation