Selected microbial diversity of contaminated landfill soil of Peninsular Malaysia and the behavior towards heavy metal exposure

Abstract

Microbes function normally and effectively when the site of action or immediate environment is intact and unpolluted. Given that microbes can significantly improve the bio-geochemical cycling of toxic heavy metals or the remediation of metal-contaminated environments, understanding the effect of microbe diversity on heavy metal pollution caused by leachate seepage is imperative. This study focused on the difference in the distribution of microbial species in non-sanitary landfill soil of Peninsular Malaysia (operational and non-operational status) regarding the heavy metal tolerance of the bacterial species. Soil and leachate characterization identified the level of pollutants in the landfill environment. Hence, microbial isolation and identification generated the microbial diversity of the contaminated landfill soils of Peninsular Malaysia. Exposure to Hg concentrations (5–20ppm) showed that all the organisms survived with a heavy growth pattern. All strains showed varied resistance to the heavy metals. Pseudomonas mendocina demonstrated the highest resistance to metal exposure. Bacillus pumilus was absolutely resistant to the heavy metals used in the study, except Ni. A comparison of isolates from operational and non-operational landfill sites in Peninsular Malaysia suggests higher susceptibility to chromium ions than to other highly toxic metals, especially lead and mercuric ions. The behavior/response of the isolated microbes suggests suitability for enhanced bioremediation of heavy-metal-polluted environments.