ACTINOBACTERIA ISOLATES FROM TIN TAILINGS AND FOREST SOIL FOR BIOREMEDIATION OF HEAVY METALS

Abstract

HEMA TG, GETHA K, TAN GYA, LILI SAHIRA H, MUHD SYAMIL A & NUR FAIRUZ MY. 2014. Actinobacteria isolates from tin tailings and forest soil for bioremediation of heavy metals. The aim of this study was to screen actinobacteria isolated from Bidor tin tailings for heavy metal tolerance as an early exploration into their bioremediation capabilities. As a comparison, isolates from forest soil in Pasoh were also studied for heavy metal tolerance. At the highest test concentration, rapid metal tolerance screening showed that the numbers of Hg²⁺, Cd²⁺ and Cu²⁺ tolerant isolates were less than 7% of the total isolates screened for both sites. More than 10% of total isolates screened from both sites showed tolerance to Pb²⁺, As³⁺ and Zn²⁺. The number of Ni²⁺ tolerant isolates was significantly higher for Bidor (12.6%) compared with Pasoh (6.6%). Metal toxicity assay carried out on tolerant isolates from Bidor showed that the final
metal concentrations supporting actinobacteria growth were 138.9 mmol L^-1 for Ni²⁺, 43.2 mmol L^-1 for Pb²⁺, 21.8 mmol L^-1 for Cd²⁺, 0.8 mmol L^-1 for Hg²⁺, 182 mmol L^-1 for As³⁺ and 14.1 mmol L^-1 for Cu²⁺. For Pasoh isolates, tolerance was observed at 21.8 mmol L^-1 for Cd²⁺ and 182 mmol L^-1 for As³⁺. Compared with rapid metal tolerance screening, metal toxicity assay clearly showed that metal tolerant isolates from Bidor were capable of tolerating heavy metals at a higher concentration compared with Pasoh isolates. Isolates TY046-021 and TY046-078, which showed multimetal tolerance to As³⁺, Pb²⁺ and Ni²⁺ and TY046-017, the only Hg²⁺ tolerant isolate from Bidor, should be further studied for heavy metal uptake and removal.