铁还原菌Shewanella oneidensis MR-1对铁磷复合物中铁、磷释放规律的影响

Effects of Iron-reducing Bacterium Strain Shewanella oneidensis MR-1 on the Release of Iron and Phosphorus from Iron/Phosphorus Compounds

中国南方红壤中的磷素大多以铁磷复合物的形式被固定于土壤中,磷的利用率较低。通过向土壤中添加以S.oneidensis MR^(-1)为主的生物肥料,促进土壤磷的释放,减少外源磷肥的输入,以期达到保护环境和资源节约的目的。采用室内模拟试验,在纯化学培养的条件下,采用接种S.oneidensis MR^(-1)的厌氧体系进行培养,分别以磷吸附态的水铁矿(水铁矿-磷)、磷吸附态的针铁矿(针铁矿-磷)和磷酸铁(FePO_(4-)磷)作为体系唯一的磷素和Fe(Ⅲ)来源,3种磷均为土壤中铁磷复合物的组成成分。结果表明,S.oneidensis MR^(-1)对3种铁磷复合物中的Fe(Ⅲ)产生了还原效应并将其还原成Fe(Ⅱ),且Fe(Ⅱ)质量浓度随试验时间延长总体呈先增长后稳定的变化趋势;当3组加入S.oneidensis MR^(-1)的体系Fe(Ⅱ)质量浓度均为最高时,Fe(Ⅱ)平均生成速率表现为:针铁矿(30.44 mg·L^(-1)·d^(-1))>水铁矿(21.05 mg·L^(-1)·d^(-1))>磷酸铁(6.62 mg·L^(-1)·d^(-1));3组加入S.oneidensis MR^(-1)的体系Fe(Ⅲ)质量浓度与初始质量浓度相比较均发生了改变,在针铁矿-磷-菌体系中Fe(Ⅲ)质量浓度极低,而水铁矿-磷-菌体系和磷酸铁-磷-菌体系中则大量存在Fe(Ⅲ);至试验结束时,磷酸铁-磷-菌体系中总磷质量浓度是初始时的2.3倍,而针铁矿-磷-菌和水铁矿-磷-菌体系的总磷约为初始质量浓度的1/10。因此,S.oneidensis MR^(-1)利用磷酸铁-磷的过程会促进磷的释放,使磷酸铁中磷得以活化,而利用针铁矿-磷和水铁矿-磷的过程则会消耗磷,不会造成磷累积。

In South China, phosphorus （P） is largely fixed as iron/phosphorus （Fe/P） compounds in the red soils with a low P utilization rate. In this study, for environmental protection and resource conservation, biofertilizer with Shewanella oneidensis MR-1, an iron-reducing bacterium strain, as its main component, was added to the soil in order to enhance soil P release and reduce exogenous P fertilizer input. In the indoor stimulation experiment, anaerobic systems with MR-1 inoculated were set up to investigate the transformation of Fe（Ⅲ） and release of P during Fe（Ⅲ） reduction, with ferrihydrite-P, goethite-P, or FePO4-P as the only source of Fe（Ⅲ） and P. The results showed that S. oneidensis MR-1 reduced the 3 different Fe（Ⅲ） compounds by varying degrees; Fe（Ⅱ） mass concentration first increased with time and then stabilized; when the mass concentrations of Fe（Ⅱ） in the systems were the highest, the average Fe（Ⅱ） production rate of the 3 systems was in the order of goethite （30.44 mg·L-1·d-1）〉ferrihydrite （21.05 mg·L-1·d-1）〉 FePO4 （6.62 mg·L-1·d-1）; Fe（Ⅲ） mass concentration in the 3 systems with MR-1 inoculated changed during the incubation progress with that in the goethite-P system being extremely low while that in the other 2 systems being high; at the end of the experiment, the total P mass concentration in the FePO4 system was 2.3 times that of the initial while that in the other 2 systems was only about 1/10 of the initial. In a word, the introduction of S. oneidensis MR-1 promoted the transformation of FePO4-P and the release of P, but consumed P from ferrihydrite-P and goethite-P with no P accumulation.