Remediation of mercury (Hg)-contaminated soil by mycorrhizal technology has drawn increasing attention because of its environmental friendliness. However, the lack of systematic investigations on arbuscular mycorrhizal fungi (AMF) community composition in Hg-polluted soil is an obstacle for AMF biotechnological applications. In this study, the AMF communities within rhizosphere soils from seven sites from three typical Hg mining areas were sequenced using an Illumina MiSeq platform. A total of 297 AMF operational taxonomic units (OTUs) were detected in the Hg mining area, of which Glomeraceae was the dominant family (66.96%, 175 OTUs). AMF diversity was significantly associated with soil total Hg content and water content in the Hg mining area. Soil total Hg showed a negative correlation with AMF richness and diversity. In addition, the soil properties including total nitrogen, available nitrogen, total potassium, total phosphorus, available phosphorus, and pH also affected AMF diversity. Paraglomeraceae was found to be negatively correlated to Hg stress. The wide distribution of Glomeraceae in Hg-contaminated soil makes it a potential candidate for mycorrhizal remediation.

To study the soil genetic diversity of bacteria and fungi in different vegetation successions (grassland, shrubbery, primary forest and secondary forest) from the karst area, the Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) technology was applied. The results showed that: (1) the diversity of bacterial communities and the fungal communities in karst area were higher than non karst area in each vegetation succession. Compared with the survey from bacterial (the Shannon index was 2.97 in primary forest, 2.91 in secondary forest, 3.18 in shrubbery, 3.14 in grassland and 2.68 in non karst), fungal diversity between karst areas (the Shannon index was 3.56 in primary forest, 3.78 in secondary forest, 3.73 in shrubbery and 3.70 in grassland) and non karst areas (the Shannon index was 3.08) was more evident, which may be related to the alterations of the composition of plant community and the source of carbon in soil with the vegetation succession of karst ecosystem; (2) The comparation of bacterial diversity index and the richness comprehensively evaluated as follows: shrubbery > grassland > primary forest > nsecondary forest. The diversity index and the richness of fungal communities was as follows: secondary forest > shrubbery > grassland > primary forest. The results suggest that the fungal communities have been greatly changed via vegetation successions, but the diversity index and the richness of the bacterial communities have not been seriously affected. The results provide scientific basis for understanding karst surface ecosystem, which contributes to the future aim of protecting the karst from desertification.