Characterization and transcriptomic analysis of a highly Cr(VI)-resistant and -reductive plant-growth-promoting rhizobacterium Stenotrophomonas rhizophila DSM14405T
2020
Gao, Jie | Wu, Shimin | Liu, Ying | Wu, Shanghua | Jiang, Cancan | Li, Xianglong | Wang, Rui | Bai, Zhihui | Zhuang, Guoqiang | Zhuang, Xuliang
Previous research has shown that Stenotrophomonas has the ability to reduce Cr(VI). In this study, we determined whether the reduction capacity of Cr(VI) is conserved in Stenotrophomonas rhizophila DSM14405ᵀ, a plant-growth-promoting rhizobacterium (PGPR). Our results show that S. rhizophila DSM14405ᵀ displays high Cr(VI) resistance at a minimal inhibitory concentration of 1000 mg/L. Furthermore, it completely reduced 50 mg/L Cr(VI) in 28 h at pH 7.5 at 30 °C. The results of X-ray photoelectron spectroscopy and high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry analysis confirmed the ability of S. rhizophila DSM14405ᵀ to convert Cr(VI) to Cr(III), and indicated the adsorption and intracellular accumulation of Cr(III). Transcriptomic analysis revealed that in the presence or absence of Cr(VI), transcriptomes upon short-term exposure showed more differentially expressed genes than those after long-term exposure. GO and KEGG analyses showed that most of the differentially expressed genes were related to Cr(VI) resistance, including genes related to iron homeostasis, central metabolism, DNA repair and anti-oxidative stress, and sulfur metabolism. Highly Cr(VI)-resistant and reductive abilities of this PGPR strain render it a suitable candidate for combined plant-microbe remediation of chromium contaminants from soil.
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