电子穿梭物质对异化Fe(Ⅲ)还原过程的影响

Effects of electron shuttle on dissimilatory iron reduction in paddy soils

选择采自吉林(JL)、四川(SC)、江西(JX)和浙江(ZJ)的水稻土样品,采用微生物混合培养和土壤泥浆厌氧恒温培养的方法,研究了电子穿梭物质蒽醌-2,6-二磺酸盐(AQDS)对异化铁还原的影响。用Logistic方程对异化铁还原过程进行模拟,并对异化铁还原特征及Fe(Ⅲ)还原的最大累积量(a)、反应速率常数(c)、最大反应速率(Vmax)等参数进行了比较。结果表明,在微生物混合培养试验中。添加AQDS能够明显加速Fe(Ⅲ)的还原,随着AQDS浓度的增大,Fe(Ⅱ)产生的速率越大,且在铁还原反应中不同来源微生物对AQDS的敏感性不同。在土壤泥浆培养中,添加AQDS可明显增大Fe(Ⅱ)累积量,并且随着AQDS浓度增大,在JX和ZJ水稻土中表现出a值不断增大,其中JX水稻土的增加幅度最大,而JL和SC水稻土的a值则随AQDS浓度增大而减小;除JL水稻土外,其他水稻土中铁还原速率常数均随着AQDS浓度的增加呈先增加后降低的趋势,表明过量的AQDS对土壤中的铁还原反应具有一定的毒害作用。试验证明AQDS不仅能促进微生物对土体中易还原氧化铁的还原,而且也能使部分较难还原的晶体氧化铁被还原。

Effects of electron shuttle on dissimilatory iron reduction in paddy soils was investigated on basis of paddy soil sampled from different areas by using co-culture incubation and soil slurry anaerobic incubation method in this paper. Logistic model was used to simulate the dissimilatory iron reduction process,effect of electron shuttle （in case of AQDS） was investigated and compared among different soils according to parameters of dissimilatory iron reduction,the maximum accumulation of Fe（ Ⅱ ）（α）, the rate constant of reduction process （c）, and the maximum rate of the reduction （Vmax）. The obtained results showed the reduction of iron（ Ⅲ ） oxides was promoted with addition of AQDS in co-culture incubation,the rate of Fe（ Ⅱ ） production increased with the increasing amount of AQDS added,and different sensitivity of iron reduction due to microbes from different soils. The accumulation of Fe（ Ⅱ ）（α）increased with the increasing amount of AQDS added in the soil slurry incubation. Amplification of the maximum accumulation of Fe（ Ⅱ ）（α） in JX and ZJ paddy soils increased with the increasing AQDS amount, especially in the JX paddy soil. But,amplification of the accumulation of Fe（ Ⅱ ）（α） in JL and SC paddy soils decreased with the increasing amount of AQDS. Except paddy soil sampled from Jilin, the rate constant of the reduction increased with the amount of AQDS added, then decreased with excess added of AQDS, which shows that excessive addition of AQDS maybe inhibit the dissimilatory reduction of iron oxides in the paddy soils. The obtained results suggests that AQDS can enhance the dissimilatory reduction of iron oxides facilitated to reduce, and can promote the reduction of partial crystal iron oxides which was difficult to reduce under normal conditions.