两头毛根际耐镉细菌的分离及生物学特性研究

Isolation and Biological Characteristics of Cd-tolerant Bacterial Strains from Rhizosphere Soil of Incarvillea arguta

为获得耐镉细菌资源,采集煤矸山优势植物两头毛根际土壤经50 mg/L Cd^(2+)培养分离出耐镉细菌,并采用形态观察、生化指标测定和16S rRNA测序对这些菌株进行鉴定,同时还对Cd^(2+)耐受范围筛选及生物学特性进行了研究。研究共分离出N-1-2、N-2-1和N-3-13种耐镉细菌菌株,分别被鉴定为假单胞菌属(Pseudomonas sp.)、微小杆菌属(Exigu⁃obacterium sp.)和芽孢杆菌属(Bacillus sp.)菌株。生长曲线结果表明菌株N-2-1在Cd2+浓度高于150 mg/L时生长受抑制,而菌株N-1-2和N-3-1分别在高于200 mg/L和150 mg/L Cd^(2+)浓度时生长完全被抑制。3种细菌在无镉胁迫下最适生长条件为N-1-2:pH=7.0和2%NaCl;N-2-1:pH=8.0和0%NaCl;N-3-1:pH=8.0和l%NaCl。在50 mg/L镉胁迫下的最适生长条件为N-1-2:pH=5.0和4%NaCl;N-2-1:pH=7.0和2%NaCl;N-3-1:pH=7.0和0%NaCl。这些结果表明菌株N-1-2和N-2-1在镉胁迫下提高了对盐的耐性,而菌株N-3-1在镉胁迫下却降低了对盐的耐性。

To obtain Cd-tolerant microbial resources,rhizosphere soils of Incarvillea arguta which is a dominant plant growing on the coal gangue pile in Liupanshui were collected to screen Cd-tolerant bacterial strains based on a medium containing 50 mg/L Cd^(2+).These isolated strains were identified via morphological and biochemical characteristics and 16S rRNA sequence analysis and their Cd^(2+) tolerance range and biological characteristics were analyzed as well.Our results indicated that a total of three Cd-tolerant bacterial strains(N-1-2,N-2-1 and N-3-1)were isolated and identified as Pseudomonas sp.,Exiguobacterium sp.,Bacillus sp.,respectively.The growth curve indicated that the growth rate of the strain of N-2-1 was obviously inhibited by 150 mg/L cadmium treatment,while two other strains were totally inhibited by more than 150 mg/L cadmium treatment.The biological characteristics of three strains cultured in a medium with no cadmium indicated that the optimum growth conditions were pH=5.0 and 4%NaCl for N-1-2;pH=7.0 and 2%NaCl for N-2-1 and pH=7.0 and 0%NaCl for N-3-1.When three strains were cultured in containing a medium with 50 mg/L of cadmium,their optimum growth conditions were pH=5.0 and 4%NaCl for N-1-2;pH=7.0 and 2%NaCl for N-2-1 and pH=7.0 and 0%NaCl for N-3-1.