钒钛磁铁尾矿土壤中水黄皮根瘤菌铁耐受性与钝化能力研究

铁是好氧微生物生长所必需的元素,而铁污染土壤环境中的根瘤菌是否对高浓度铁具有耐受性和钝化能力尚不清楚。以攀枝花钒钛磁铁尾矿土壤作为基质进行水黄皮共生根瘤菌捕获实验,获得水黄皮共生根瘤并从中分离纯化出根瘤菌39株。通过Fe 2+/Fe 3+耐受性和钝化能力测试筛选出耐受性和钝化能力均强的优势菌株PZHS20、PZHS90、PZHS87,其对Fe 2+的最大耐受质量浓度为1600 mg/L,其中PZHS20在200 mg/L Fe 2+溶液中钝化效率最大,为73.54%;PZHS90对Fe 3+的最大耐受质量浓度为1600 mg/L,而PZHS20和PZHS87对Fe 3+的最大耐受质量浓度为1800 mg/L,其在200 mg/L Fe 3+溶液中钝化效率分别为84.25%和81.95%。16S rRNA基因系统进化分析将PZHS20鉴定为苍白杆菌(Ochrobactrum),将PZHS90和PZHS87鉴定为慢生根瘤菌(Bradyrhizobium)。研究结果表明,钒钛磁铁尾矿土壤中的水黄皮根瘤菌具有不同程度的Fe 2+/Fe 3+耐受性和钝化能力,筛选出的优势菌株为进一步利用水黄皮-根瘤菌联合修复高浓度铁污染土壤提供可利用的菌株资源。

Iron Tolerance and Passivation Capability of Pongamia pinnata Symbiotic Rhizobium in Vanadium-Titanium Magnetite Tailings Soil

Iron is an essential element for the growth of aerobic microorganisms, however, it is still not clear whether rhizobia in iron-polluted soil have tolerance and passivation ability to high concentrations of iron. In this study, the vanadium titanium magnetite tailings soil in Panzhihua was taken as the substrate for capturing experiment of Pongamia pinnata symbiotic rhizobium, and obtained rhizobium symbiosis nodules, and isolated and purified a total of 39 rhizobia strains from the nodules. The dominant strains PZHS20, PZHS90 and PZHS87 with strong tolerance and passivation ability were screened by testing the tolerance and passivation ability of Fe²⁺/Fe³⁺. The maximum tolerance concentration of PZHS20 to Fe²⁺ was 1 600 mg/L, and PZHS20 showed the highest passivation efficiency with 73.54% in 200 mg/L Fe²⁺ solution. The maximum tolerance concentration of PZHS90 to Fe³⁺ was 1 600 mg/L, while the maximum tolerance concentration of PZHS20 and PZHS87 to Fe³⁺ was 1 800 mg/L, and their passivation efficiency in 200 mg/L Fe³⁺ solution was 84.25% and 81.95%, respectively. According to phylogenetic analysis of 16S rRNA genes, PZHS20 was identified as Ochrobactrum, and both PZHS90 and PZHS87 were identified as Bradyrhizobium. The results suggested that Pongamia pinnata symbiotic rhizobia in vanadium titanium magnetite tailings soil had different degrees of Fe²⁺/Fe³⁺ tolerance and passivation ability, and the screened dominant strains could provide available strain resources for the further utilization of Pongamia pinnata and rhizobia to unite-remedy the polluted soil caused by high concentration of iron.