摘  要：本研究从镉污染水稻根际土壤中分离、纯化出一株耐镉菌134，并对该菌株的生理生态特征、16S rDNA等进行了系列分析，结果表明该菌株为气单胞菌（Aeromonas sp.），革兰氏阴性，对镉离子的耐受质量浓度为75 mg/L。选取水稻根系的常见分泌物氨基酸和糖类作为外源趋化剂考察气单胞菌134对各组分的趋化性，结果表明，菌株134对组氨酸、丙氨酸、亮氨酸、葡萄糖及果糖均具有较强的正趋化性。类毛细血管定量试验进一步表明，菌株134对不同浓度趋化剂的响应不同，在亮氨酸80 μmol/L、组氨酸40 μmol/L、丙氨酸60 μmol/L、葡萄糖60 μmol/L及果糖100 μmol/L时，菌株134的趋化性最强。综合考虑滴定分析试验和类毛细血管试验结果，本文设计了水培试验来研究外源添加适宜浓度的组氨酸、亮氨酸、葡萄糖及D-果糖对菌株134在水稻根际定殖的影响。试验结果表明，这4种外源趋化剂均能促进菌株134在水稻根际的定殖，尤其是葡萄糖和D-果糖的处理，其根际定殖细菌数量与对照相比差异极显著（P<0.01），分别为对照组的3.48和3.87倍。

Abstract: In this study, a cadmium-resistant strain 134 was isolated and purified from the rice rhizosphere soil polluted by cadmium. The physiological and biochemical characteristics and 16S rDNA were studied. The results showed that strain 134 was a Gram-negative strain and can grow under the concentration of 75 mg/L cadmium. Analysis of 16S rDNA sequence of strain 134 showed it belongs to Aeromonas sp. Amino acids and sugars was chosen as the exogenous chemotacticum, which is the commonly exudates in rice root, and the chemotactic reaction of Aeromonas 134 with the exogenous chemotacticum was investigated. The results showed that Aeromonas 134 has strong positive chemotaxis to histidine, alanine, leucine, glucose and fructose. Capillary tube test suggested that the chemotaxis responses of strain 134 depended on the concentrations of the chemotacticum. In detail, strain 134 showed the strongest chemotactic reaction towards the 80 μmol/L leucine, 40 μmol/L histidine, 60 μmol/L alanine and glucose, 100 μmol/L fructose. On the basis of these, a solution culture experiment was designed to study the effects of exogenous addition of histidine, leucine, glucose and D-fructose on the colonization of strain 134 in the rice rhizosphere. All four exogenous chemotactic agents can promote the colonization of strain 134 in the rice rhizosphere, especially the treatment of glucose and D-fructose, the number of rhizosphere colonizing bacteria was significantly different from the control (P <0.01), and was 3.48 and 3.87 times of the control, respectively.