产多胺细菌阻控空心菜富集Cd和Pb效应

通过产多胺筛选培养基，借助超高效液相色谱技术，本研究从重金属污染农田空心菜根际土壤中筛选具有钝化重金属的产多胺细菌，并通过水培试验研究功能菌株对空心菜生长、多胺含量和抗氧化酶活性以及Cd和Pb吸收的影响.结果显示，从空心菜根际土壤中共分离到9株高产多胺的细菌菌株，其中Enterobacter bugandensisYX6能够分泌精胺和亚精胺，Klebsiellaquasivariicola YX8能够分泌腐胺.在LB培养基中，菌株YX6和YX8对Cd和Pb吸附去除率均大于80%.水培试验表明菌株YX6和YX8能够显著提高空心菜地上部和根部多胺（29.3%~180%）的含量以及可食用部分超氧化物歧化酶（18.5%-42.7%）和过氧化物酶（46.2%~100%）的活性，进而显著提高了空心菜地上部（21.2%~40.9%）和根部（43.3%~68.2%）的干重，同时降低了空心菜地上部和根部Cd（45.8%~69.5%）和Pb（42.4%~63.6%）的含量.产多胺细菌E.bugandensisYX6和K.quasivariicola YX8不仅能够提高空心菜生物量和抗氧化酶活性，还能低空心菜对Cd和Pb的吸收，为重金属超标农田安全利用和减少蔬菜中的重金属含量提供菌种资源.

Screening of polyamine-producing bacteria and their effects on reducing Cd and Pb accumulation in Ipomoea aquatica

Polyamine-production screening media and ultra performance liquid chromatography (UPLC) were used to isolate polyamine-producing bacteria from Cd- and Pb-pollutedrhizospheresoil ofIpomoea aquatica. The effects of functional strains on the growth, polyamine content, antioxidant enzyme activity and Cd and Pbaccumulation of I.aquatica were studied by hydroponics experiment. Results showed that nine high polyamine-production strains were isolated from the rhizosphere soil of I.aquatica. Among them, srainEnterobacter bugandensisYX6secreted spermine and spermidine, strain Klebsiellaquasivariicola YX8secreted putrescine. The adsorption rates for strains YX6and YX8to Cd and Pb were more than 80% in LB medium solution.Hydroponics experiment showed that strain YX6 and YX8significantly increased the content of polyamines (29.3%~180%) and the activities of superoxide dismutase (18.5%~42.7%) and peroxidase (46.2%~100%) in I.aquatica shoots and roots, and significantly increased the dry weight of shoots (21.2%~40.9%) and roots (43.3%~68.2%), and reduced the Cd (45.8%~69.5%) and Pb (42.5%~63.6%) contents in I.aquatica shoots and roots.Polyamine-production bacteria E. bugandensisYX6and K. quasivaricolaYX8not only improved the biomass and antioxidant enzyme activity of I.aquatica, but also reduced the absorption of Cd and Pb by I.aquatica, which provides bacterial resources for the safe utilization of heavy metals in farmland and the reduction of heavy metals content in vegetables.