Community composition and functional characteristics of bacteria in the rhizosphere of Kalidium foliatum from the radiation polluted area

Abstract:

[Background] Source of radiation-resistant microorganisms is rich in Chinese radiation-polluted area in Northwest China, where some places are covered with Kalidium foliatum (Pall.) Moq. Salt accumulation constructed a salt island in the rhizosphere of Kalidium foliatum. Therefore, it will be important to collect the microbial resources and to reveal the mechanism of salt adaptability and salt island formation for Kalidium foliatum. [Objective] We analyzed the bacterial composition in the rhizosphere of Kalidium foliatum from the radiation-polluted area, and investigated the microbial resources and their functional properties. [Methods] Based on traditional culture methods, rhizosphere microorganisms were isolated using 10 culture media, and identified by 16S rRNA gene sequence analysis. Then characteristics of the resistance, enzyme producing and plant growth promoting were tested. [Results] A total of 267 isolates were obtained, and classified into 20 genera from Actinobacteria, Proteobacteria and Firmicutes. Isolates from Actinobacteria were dominant component involving 9 genera. Eight potential novel species were discovered. Bacterial diversity was rich in the rhizosphere of Kalidium foliatum. The resistance analysis of strains showed that more than 70% of the representatives could tolerant 10% NaCl, and 40% of them were resistant to different heavy metal ion. At the same time, several isolates producing protease, lipase, amylase and cellulase were observed, and some plant growth promoting bacteria were obtained, which provide important material to further screening industrial enzyme and developing microbial fertilizer. [Conclusion] Valuable microbial resources existed in the rhizosphere of Kalidium foliatum.

Key words:Radiation-polluted area, Kalidium foliatum, rhizosphere bacteria