Abstract: Contamination of environments by heavy metals and radionuclides has become a serious problem worldwide．The treatment of heavy metals and radionuclides in environments by specific microorganisms such as meta1-reducing and metal-resistant bacteria has become promising technology．The successful application of in-situ bioremediation will provide potential ways to clean up heavy metals and radionuclides in contaminated environments．Recent studies also focus on understanding the effect of heavy metals and radionuclides on the microorganisms in the microbial community．Microbial mats and biofilms are two representative microbial communities functioning in bioremediation．Metal speciation and valence variation, transport processes，and microbial metabolism are three important ingredients for metal and radionuclide remediation．Combining these ingredients enables us to better understand the relationships between the naturally occurring microorganisms and bioremediation processes．