Diversity of endophytic and rhizospheric bacteria of Suaeda heteroptera Kitag from Panjin Delta in Liaoning Province

Abstract:

[Objective] Suaeda heteroptera Kitag which is a typical saline indicator plant has the function of restoring the saline-alkali soil polluted by heavy metals and oil. But little was known about the relationship between its root and endophytic microorganisms, microbial diversity and the function of rhizospheric microorganisms in bioremediation. In this study, we determined the diversity and structure of the endophytic and rhizospheric bacteria of Suaeda heteroptera Kitag from delta area in Panjin Liaoning Province. [Methods] The bacterial diversity in rhizosphere soil, root homogenate and root attachments of Suaeda heteroptera Kitag was analyzed by traditional culture methods and high-throughput sequencing. The selected strains were identified by morphological observation and analysis of 16S rRNA gene sequences and physio-biochemical characteristics. [Results] Sixty-seven strains were isolated from these three samples with traditonal methods, and twenty-eight strains among them were selected as the representative strains. The results showed that the strains were mainly affiliated with the genus Halomonas, Marinobacterium, Bacillus, Paracoccus, Pseudomonas, Planococlus, Serratia and Zhihengliuella. High-throughput sequencing analysis showed that these three samples with highest bacterial diversity were, in order, root attachments, rhizosphere soil and root homogenate. In total, twelve phyla were identified from these samples, which were Acidobacteria, Actinobacteria, Bacteroidetes, Chlorobi, Chloroflexi, Cyanobacteria, Firmicutes, Gemmatimonadetes, Planctomycetes, Proteobacteria, Spirochaetes and Verrucomicrobia. Bacteria assemblage was dominated by Cyanobacteria (42%) and Proteobacteria (33%) in root homogenate. Proteobacteria (46%) and Bacteroidetes (16%) were the predominant phyla in root attachments. Bacteroidetes (37%) and Proteobacteria (20%) were the predominant phyla in rhizosphere soil. [Conclusion] The diversity of endophytic and rhizospheric bacteria of Suaeda Heteroptera Kitag is high, which suggests that the bateria in this environment may play a role in the bioremediation of saline-alkali soil polluted by heavy metals and oil.