Isolation, Identification and Selenium Tolerance Assay of Endophytic Microbes from Selenium Hyperaccumulator Cardamine violifolia
GENG Zhi1,2, WANG Li-Ping2, FENG Yu-Qi2, SUN Yan-Mei2, WANG Shi-Wei2,*, SHEN Li-Xin2
1 School of Medicine, Shaanxi Institute of International Trade Commerce, Xi'an 712046, China; 2 School of Life Science, Northwest University, Xi'an 710069, China
Abstract：Cardamine violifolia is a selenium hyperaccumulator, which was discovered to be medicinal and edible by Chinese scientists. It can convert inorganic selenium into selenocysteine and accumulate selenium in plant. Microorganisms can transform selenium forms, and this transformation may be beneficial to selenium enrichment in C. violifolia. However, there are few studies on the endophytes of C. violifolia. In this work, the endophytes from C. violifolia were isolated and identified, and the selenium resistance was investigated. Finally, 6 endophytic bacteria were purified from C. violifolia and 4 strains were capable of producing nano-selenium by metabolizing 0.01 mol/L sodium selenite. Enterobacter sp. SX-18 was identified to be resistant to a concentration of up to 0.20 mol/L sodium selenite, and was able to transform 46.96% of 0.02 mol/L sodium selenite into nano-selenium in 24 h. A total of 5 endophytic fungi were isolated and identified. All of them displayed the ability to metabolize 0.01 mol/L sodium selenite, and Colletotrichum sp. SZ-5 was identified to be resistant to 0.16 mol/L sodium selenite and was able to transform 19.34% of 0.02 mol/L sodium selenite into nano-selenium in 48 h. The present study provides more endophytic microbial resources for investigating the interaction between plants and microorganisms and biological remediation of selenium contamination aera.
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