Application Of Endophytic Bacterium Isolated From Cd Hyperaccumulator Solanum Nigrum L For Heavy Metal Wastewater

Heavy metal pollution by industrial activities and technological development isposing significant threats to the environment and public health because of its toxicity,non-biodegradability and bio-accumulation. Trace of heavy metals such as cadmium(Cd (II)), lead (Pb (II)), copper (Cu (II)) and chromium (Cr (VI)), which arecommonly presented in contaminated soils, can enhance Fe deficiency symptoms bothin microbes and plants, thus affecting their growth negatively. Furthermore, they cancombine with sulfhydryl groups of proteins, restraining the activity of enzymes. Thepermanent existences of cadmium (Cd (II)), lead (Pb (II)), copper (Cu (II)) andchromium (Cr (VI)) in polluted ecosystems threaten the health of entire human beingsall the time.Bioremediation, which involves the use of microbes to detoxify and degradeenvironmental contaminants, has received increasing attention in recent times to cleanup a polluted environment. Bioremediation, being in situ treatment, provides a safeand economic alternative to commonly used physicochemical strategies.Heavy metal bioremediation by a multi-metal resistant endophytic bacteria L14(EB L14) isolated from the cadmium hyperaccumulator Solanum Nigrum L. wascharacterized for its potential application in metal treatment.16S rDNA analysisrevealed that this endophyte belonged to Bacillus sp. The hormesis of EB L14wereobserved in presence of divalent heavy metals (Cu, Cd and Pb) at a relatively lowerconcentration (10mg/L). Such hormesis was the side effect of abnormal activitiesincreases of ATPase which was planned to provide energy to help EB L14reduce thetoxicity of heavy metals by exporting the cations. Within24h incubation, EB L14could specifically uptake75.78%,80.48%,21.25%of cadmium, lead and copper atthe initial concentration of10mg/L. However, nearly no chromium uptake wasobserved. The mechanism study indicated that its remediation efficiencies may begreatly promoted through inhibiting the activities of ATPase. The excellent adaptationabilities and promising remediation efficiencies strongly indicated the superiority ofthis endophyte in low concentrations heavy metal bioremediation, which could beuseful for developing efficient metal removal system.This dissertation was the first attempt to directly use heavy metalhyperaccumulator endophytes which not only possess the excellent adaptability but also have been equipped with various metal-sequestration systems for heavy metalbioremediation. This study offers the ability to fully achieve the application ofbioremediation in practical heavy metal decontamination.