Genetic diversity of endophytic bacteria of the manganese-hyperaccumulating plant Phytolacca americana growing at a manganese mine

Endophytic bacteria have great potential for assisting metal-hyperaccumulating plants in remediation of contaminated soils. However, little information is available on the composition of the endophytic bacterial community of the manganese (Mn)-hyperaccumulator Phytolacca americana. In this study, PCR-denaturing gradient gel electrophoresis was used to analyze the endophytic bacterial diversity and community composition in P. americana growing at an Mn mining site. Results showed that Mn had a significant impact on the bacterial diversity and community structure. Phylogenetic analyses of the recovered DNA sequences classified the bacteria into 10 different divisions, indicating a high level of diversity amongst the endophytic bacterial species of P. americana. Sequencing results demonstrated that Proteobacteria, specifically the γ, δ and α subclasses, may be the dominant endophytic bacterial genera of P. americana. Some unique sequence types that occurred exclusively in heavily polluted sites were worth investigating their effects on phytoremediation under Mn-contaminated soils.