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从生长在西北部分矿区的豆科植物根瘤中分离筛选到对重金属有抗性的38株根瘤菌,采用PCR-RFLP分子技术进行16S rDNA指纹图谱分析,选取每种类型的代表菌株进行16S rDNA全序列测定,建立系统发育树状图,并对38株菌进行Zn、Hg、Cu、Cd和Pb5种重金属的抗性研究。结果表明,供试菌株分别归属于中华根瘤菌属(Sinorhizobium)、根瘤菌属(Rhizobium)和土壤杆菌属(Agrobacterium)。代表菌株CCNWSX1277和CCNWSX1294可耐受2.0mmol·L-1的Zn2+,CCNWSX1277可耐受0.25mmol·L-1的Hg2+,多数代表菌株可耐受1.6mmol·L-1的Cu2+,仅3株代表菌株可以耐受Cd2+,其中CCNWSX1277能耐受1.4mmol·L-1的Cd2+,所有代表菌株能耐受2.5mmol·L-1的Pb2+。Agrobacterium属的2株代表菌株对5种重金属均有较强的耐受性;而Rhizobium属的4株菌和Sinorhizobium属的3株菌对5种重金属的耐受性不同,表现出较大的差异。总体来看,供试菌株对重金属的耐受性顺序为Agrobacterium>Rhizobium>Sinorhizobium。
Thirty-eight rhizobia strains resistant to heavy metals were isolated from the leguminous plant nodules growing in the northwestern part of the mining area. The 16S rDNA fingerprinting analysis was carried out by using PCR-RFLP molecular techniques. The representative strains of each type were selected for 16S rDNA Sequence analysis was used to establish the phylogenetic tree map. The resistance of 38 strains to heavy metals (Zn, Hg, Cu, Cd and Pb) was studied. The results showed that the tested strains belonged to Sinorhizobium, Rhizobium and Agrobacterium, respectively. Representative strains CCNWSX1277 and CCNWSX1294 could tolerate 2.0 mmol·L-1 Zn2 +, CCNWSX1277 could tolerate 0.25 mmol·L-1 Hg2 +, most of the representative strains could tolerate 1.6 mmol·L-1 of Cu2 +, only 3 representative strains Which can tolerate Cd2 +. Among them, CCNWSX1277 can tolerate 1.4mmol·L-1 Cd2 +, and all the representative strains can tolerate 2.5mmol·L-1 Pb2 +. The two strains of Agrobacterium were highly tolerant to five kinds of heavy metals, while the four strains of Rhizobium and Sinorhizobium were different in tolerance to five kinds of heavy metals, showing great difference . In general, the order of tolerance of the tested strains to heavy metals was Agrobacterium> Rhizobium> Sinorhizobium.