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为获得稻田土壤镉污染修复的微生物,采用培养基加镉平板法,从水稻根际土壤分离耐镉细菌。本研究分离得到3株耐镉菌株,经16S rDNA测序、比对,鉴定为假单胞菌属细菌。对菌株细胞形态的电镜观察、菌株生长曲线的测定结果表明,在镉处理浓度为100 mg L 1条件下,菌株生长未受明显抑制,但菌株形态发生了适应性的变化;在镉处理浓度超过300 mg L 1时,菌株生长受到明显抑制;在镉处理浓度700 mg L 1条件下,菌株仍能生长,但生长延滞期延长,对数期后的生长量亦低;对菌体镉含量分析表明,在100 mg L 1镉处理下,3株菌株菌体中的镉含量分别为9.04 mg g 1、4.96 mg g 1和28.58 mg g 1,富集系数依次为90.4、49.6和285.8。可见,分离得到的3株菌株具有较强镉耐性和镉吸收能力,将为稻田土壤重金属镉污染的修复提供重要微生物资源。
In order to obtain the microorganisms repaired by soil cadmium pollution in paddy soil, cadmium-tolerant bacteria were isolated from rhizosphere soil of rice by using culture medium plus cadmium plate method. In this study, three strains of cadmium-tolerant bacteria were isolated and sequenced. The 16S rDNA sequences were compared and identified as Pseudomonas bacteria. The electron microscopic observation of the cell morphology of the strain and the determination of the growth curve of the strain showed that the growth of the strain was not significantly inhibited under the condition of cadmium treatment at a concentration of 100 mg L -1 but that the strain morphology was adaptively changed. At 300 mg L 1, the growth of the strain was significantly inhibited. Under Cd concentration 700 mg L -1, the strain could still grow but the growth retardation period was prolonged and the growth rate was also lower after the logarithmic phase. The results showed that the cadmium contents of the three strains were 9.04 mg g, 1,4.96 mg g 1 and 28.58 mg g 1, respectively, with the enrichment coefficients of 90.4, 49.6 and 285.8 in the order of 100 mg L -1 cadmium. It can be seen that the three strains isolated have strong cadmium tolerance and cadmium absorption capacity and will provide important microbial resources for the remediation of heavy metal cadmium pollution in paddy soil.