抗镉细菌分离鉴定及其对镉胁迫水稻幼苗生长的影响
Isolation and Identification of Cadmium-Resistant Bacteria and Their Influence on Growth of Cadmium-Stressed Rice Seedlings

目的：旨在分离筛选有利于水稻种植的抗镉菌种资源。方法：从水稻根际土壤分离纯化抗镉细菌，采用火焰原子吸收分光光度法测定菌株对镉的吸附去除率，利用水培法检测抗镉细菌对镉胁迫水稻幼苗生长的影响，运用16S rRNA基因序列分析来鉴定菌株的种属。结果：分离得到4株抗镉细菌Cdr-1~Cdr-4，其中菌株Cdr-2在含镉400 mg/L的培养液生长后，对镉离子吸附去除率为61.27%。菌株Cdr-2对无镉水稻营养液中培养的水稻幼苗具有促生长作用，但它对受10 mg/L镉离胁迫的水稻幼苗生长有加强毒害作用。经16S rRNA基因测序鉴定菌株Cdr-2为产气克雷伯氏菌。结论：从水稻根际土壤分离出一株兼有抗镉性和促生长性的产气克雷伯氏菌Cdr-2。意义：研究结果可为产气克雷伯氏菌Cdr-2在水稻种植上应用提供参考。
Aim: Isolating and screening of the cadmium-resistant bacteria (Cd-r-BA) that were benefited to rice cultivation. Methods: The Cd-r-BA was isolated from rice rhizospheric soil. The adsorption and removal rate of cadmium when the Cd-r-BA grows in cadmium-containing broth was detected by the flame atomic absorption spectrometric method. The effects of Cd-r-BA to cadmium-stressed rice seedlings were detected by using water culture method. The identification of the object bacterium was depended on its 16S rRNA gene sequence. Results: The results showed that four Cd-r-BA strains of Cdr-1~Cdr-4 were screened out. Especially, when the strain Cdr-2 grows in broth containing 400 mg/L of cadmium, the adsorption and removal rate of 61.27% cadmium was detected. The growth of the rice seedlings was prompted by the strain Cdr-2 under cadmium-free rice culture nutrients in water culture box, while the toxic effects of the cadmium to the rice seedlings was enhanced by the strain Cdr-2 under 10 mg/L of cadmium condition. The strain Cdr-2 was identified as species Klebsiella aerogenes by 16S rRNA gene sequencing. Conclusion: The conclusion was drawn that a Klebsiella aerogenes strain Cdr-2 that characterized by cadmium-resistance and growth-promoting was isolated and screened from rice rhizosphericsoil. Significance: The results could provide reference data for the application of strain Cdr-2 to the rice cultivation.