Effect of arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) on microbial community composition 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 composition in soils planted with tall fescue ( Festuca elata ), four treatments were set up in phenanthrene (PHE) and pyrene (PYR) contaminated soil: tall fescue (CK), AMF + tall fescue (GV), PGPR + tall fescue (PS), and AMF + PGPR + tall fescue (GVPS). Our results showed that the 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 proliferation in tall fescue rhizosphere soil. Paired-end Illumina HiSeq analysis of the 16S rRNA gene and Internal Transcribed Spacer (ITS) region sequences was used to assess changes in the bacterial and fungal communities composition of the four treatments. GVPS positively affected the species 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 and Meyerozyma were the richest bacterial and fungal genus in all treatments, respectively, whereas Sphingomonas and Fusarium were the dominant bacterial and fungi genus in GVPS. Overall, our findings revealed that application of Glomus versiforme and Pseudomonas fluorescens , Ps2-6 had an effective role in improving the growth characteristics, root infection of F. elata and soil microbial community composition in PHE and PYR contaminated soils, but no obvious in degradation efficiencies of PHE and PYR as compared to the control.