Distribution heterogeneity of Bacillus-like species in endophyte and rhizosphere of subtropical crops based on culturable method

Abstract:

[Background] Bacilllus-like species are important microbial inoculants in agriculture to promote plant growth, prevent disease and insect. [Objective] To study Bacillus-like species community of several subtropical plant endophyte and rhizosphere soil, providing scientific foundation for mining Bacillus-like species. [Methods] On the basis of the culturable method, Bacillus-like species were isolated from roots and rhizosphere soil samples of Saccharum officinarum, Hibiscus cannabinus L., Corchorus capsularis L., Abelmoschus esculentus, and Hibiscus sabdariffa. Then, the isolates were identified by 16S rRNA gene and phylogenetic tree was constructed to explore the relationship between isolates and their related type species. [Results] There were 144 isolates obtained, including 82 isolates of endophytic bacteria and 62 isolates of rhizosphere bacteria, which were identified as 37 species of 4 genera, including Bacillus, Brevibacillus, Lysinibacillus, and Paenibacillus through 16S rRNA gene sequencing. The dominant genus was Bacillus, and the second one was Paenibacillus. There was great difference of the species number and colonies content in the root and rhizosphere soil. The colonies content in the rhizosphere was greater than roots. The colonies content range of Bacillus-like species in rhizosphere was (0.2?370.0)×105 CFU/g, but (0.1?81.0)×103 CFU/g in the root. Species number in roots was much larger than rhizosphere, which 19 species were obtained from rhizosphere and 32 were from roots. Bacillus aryabhattai, Bacillus mesonae and Bacillus pseudomycoides were both distributed in the 4 crop’s roots and rhizosphere, other species only occurred in the one crop’s roots or rhizosphere. [Conclusion] there were rich Bacillus-like species number and abundant content in the crop’s rhizosphere and roots, and several culturable potential novel Bacillus species, providing the theoretical base and scientific foundation for interaction of plant-microbe and ecological balance of rhizosphere environment.