Endophytic Bacteria in Ricinus communis L.: Diversity of Bacterial Community, Plant−Growth Promoting Traits of the Isolates and Its Effect on Cu and Cd Speciation in Soil

Ricinus communis L. shows certain tolerance to and good accumulation ability with heavy metals. Endophytic bacteria−enhanced phytoremediation is an effective method improve metal extraction efficiency. Here, for better application of castor in phytoremediation, the Illumina high−throughput sequencing was carried out reveal endophytic bacterial community tissues grown two locations, traditional microbial cultivation used isolate bacteria from castor. The dominant phyla were Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes Acidobacteria, Proteobacteria absolutely dominate all tissues. There significant differences composition communities between sites, obvious variation relative abundance phylum. samples sites also had their own unique genera. analysis alpha diversity illustrated that species richness different parts sampled Tonglushan mining area lower than those Gangxia village, Yangxin county. In total, there 44 strains isolated castor, which 42 possessed three or more growth−promoting properties. Most these isolates tolerant Cu Cd varying degrees. Eight selected further mobilization soil incubation experiments. Strains TR8, TR18, TR21, YL1, YS3 YS5 could well solubilize Cu2(OH)2CO3 medium. Strain best effect on increasing DTPA−Cu DTPA−Cd contents by 8.4% 6.9%, respectively. Inoculated conducive conversion forms insoluble relatively unstable, increase available phosphate content (10.8–29.2%). Therefore, plant endophytes screened have great prospects can provide important support microbial−assisted metal−contaminated soil.