Effect of arbuscular mycorrhizal fungi (AMF) and plant growth promoting rhizobacteria (PGPR) on microbial community structure of phenanthrene and pyrene contaminated soils using Illumina HiSeq sequencing

In order to determine the influence of arbuscular mycorrhizal fungi (AMF, Glomus versiforme) and plant growth promoting rhizobacteria (PGPR, Pseudomonas fluorescens, PS2-6) on degradation of phenanthrene (PHE) and pyrene (PYR) and the change of microbial community structure in soils planted with tall fescue (Festuca elata), four treatments were set up in phenanthrene (PHE) and pyrene (PYR) contamined soil: i.e., tall fescue (CK), AMF + tall fescue (GV), PGPR + tall fescue (PS) and AMF + PGPR + tall fescue (GVPS), PHE and PYR dissipation in the soil and accumulated in the tall fescue were investigated. Our results showed that highest removal percentage of PHE and PYR in contaminated soil as well as biomass of tall fescue were observed in GVPS. PHE and PYR accumulation by tall fescue roots were higher than shoots, the mycorrhizal status was best manifested in the roots of tall fescue inoculated with GVPS, and GVPS significantly increased the number of PGPR colonization in tall fescue rhizosphere soil. And paired-end Illumina HiSeq analysis of 16S rRNA and Internal Transcribed Spacer (ITS) gene amplicons were also employed to study change of bacterial and fungal communities structure in four treatments. GVPS positively affected the speices and abundance of bacteria and fungi in PHE and PYR contaminated soil, an average of 71,144 high quality bacterial 16S rDNA tags and 102,455 ITS tags were obtained in GVPS, and all of them were assigned to 6,327 and 825 operational taxonomic units (OTUs) at a 97% similarity, respectively. Sequence analysis revealed that Proteobacteria was the dominant bacterial phylum, Ascomycota was the dominant fungal phylum in all treatments, whereas Proteobacteria and Glomeromycota were the most prevalent bacterial and fungal phyla in GVPS, respectively. And in the generic level, Planctomyces is the richest bacterial genus, and Meyerozyma is the richest fungal genus in all treatments, whereas Sphingomona was the dominant bacterial genus, while the dominant fungi was Fusarium in GVPS. Overall, our findings revealed that application of AMF and PGPR had an effective role in improving the growth characteristics, root colonization of F. elata and soil microbial community structure in PHE and PYR contaminated soils, but no obvious in degradation efficiencies of PAHs as compared to the control.