Diversity and Mercury-resistance of Actinomycetes in Tongren, Guizhou

Diversity and mercury-resistance of Actinomycetes in the soil polluted by heavymetals at Tongren karst regeions in Guizhou were studied to gain information for environmental recovery and bioremedies. Twenty-five soil samples were collected from the areas. Microorganisms were screened on 7 different culture media with gradient concentrations of mercury under 3 different treatments to isolate the resistant strains. Subsequently, the isolates were examined for their morphological, physiological and biological characteristics, and subjected to a 16S rDNA phylogenetic an alysis for further identification.As a result, 56 typical Actinomycetes belonging to Streptomyces, Streptosporangium, Thermomonospora, Actinobacillus, Intrasporangium, Nocardia, and Micromonospora were found to be resistant to mercury.Among them, 68% were Streptomyces with one particular strain showing a high mercury-resistance to survive under a 75 mg·L^-1 up to 85 mg·L^-1 mercury stress, which was identified to be Streptomyces rameus.