The Construction of Metagenome of Metal-Contaminated River Sediments and Screening Heavy-Metal Resistant Gene

Metagenome is a fast developing cultivation independent technology, which is useful in addressing evolutionary and ecological relationship of microbial communities, also quite challenging to research function genes. Here we improved DNA extraction method and the DNA extracted is of high yield and allows direct 16S rDNA PCR amplification. we used the high-molecular-weight bacterial DNA to construct sediment metagenomic library. The metagenomic library of river sediments polluted was constructed, and then was estimated by digested clones selected randomly by BamH I. The metagenomic library containing 6,000 clones was constructed into pUC18 vector. An positive clones was selected by functional screening of the library. A Zn-Cd resistance active gene designated Mtx was identified by subcloning, sequencing and expression. This Mtx gene encodes cation-proton-antiporter belonging to Czc family, which is most related to the Czc R gene from Ralstonia sp. CH34 with 93% similarity.