厌氧培养体系中V(V)与Fe(Ⅲ)还原之间的电子竞争  

Competition for Electron Donator Between V(V)Reduction and Fe(Ⅲ) Reduction During Anaerobic Incubation

作　　者：段骏[1] 贾蓉[1] 曲东[1] 

机构地区：[1]西北农林科技大学资源环境学院,陕西杨凌712100

出　　处：《水土保持学报》2014年第3期264-270,共7页Journal of Soil and Water Conservation

基　　金：国家自然科学基金面上项目(41171204)

摘　　要：以4种不同来源的水稻土为材料,采用接种水稻土浸提液的厌氧培养试验,设置添加不同偏钒酸盐浓度和无定形氧化铁处理,测定培养过程中V（V）和Fe（Ⅱ）浓度的变化,探讨厌氧培养过程中V（V）和Fe（Ⅲ）还原之间的相互影响机制。结果表明,在厌氧环境下土壤微生物能够以V（V）作为电子受体,将其还原为低价态的钒,V（V）浓度随着培养时间增加呈降低趋势。以V（V）为唯一电子受体时,还原起始时间大体在2~15d之间;4种水稻土中的微生物群落对于V（V）的还原能力具有差异,V（V）还原率在汉中（HZ）和安康（AK）水稻土样品中分别达到92.82%~95.63%和81.15%~81.97%,而在邛崃（QL）和永吉（YJ）水稻土样品中分别为60.64%~62.19%和51.38%~53.41%,2种钒添加浓度处理间无明显差异。V（V）和Fe（Ⅲ）共同作为电子受体时,Fe（Ⅲ）可导致V（V）还原过程明显滞后15~20d,并且使还原率降低,分别为66.50%~75.26%（HZ）,67.15%~69.22%（AK）,48.14%~48.72%（YJ）及0~11.80%（QL）。不同处理的铁还原率均可达到100%,铁还原最大反应速率（Vmax）总体表现为：AK〉HZ〉QL〉YJ样品;添加不同浓度V（V）后AK、HZ和YJ样品中出现明显促进铁还原过程的＂协同效应＂,表现为Vmax增大,且最大还原速率对应的时间（TVmax）相应减小,但在QL样品中出现抑制铁还原的＂拮抗效应＂,表现为随着V（V）浓度增加Vmax减小,且TVmax增大。推测的＂协同效应＂机理为：以发酵微生物的兼性还原为主导,V（V）还原产物强化了铁还原过程;而＂拮抗效应＂可能由于专性铁还原微生物的群落演替以及钒的毒性对发酵微生物产生抑制所致。To investigate the mechanism of interaction between V （Ⅴ） reduction and Fe （Ⅲ ） reduction, anaerobic incubation experiments with microbial community extracted from four paddy soils were conducted with glucose as electron donator, amorphous iron oxide（ferrihydrite） and different concentration of ammonium metavanadate as electron acceptor. The changes of V（Ⅴ） and Fe（ Ⅱ ） concentration were monitored. The result showed that V（Ⅴ） as electron acceptor was reduced by microbes from paddy soil to a lower valence state, and V（Ⅴ） reduction resulted in a decrease trend of V（Ⅴ） concentration over incubation time. With V（Ⅴ） as the sole electron acceptor, V（Ⅴ） reduction was initiated at the 2-15 d of anaerobic incubation and theV（Ⅴ） reduction rate was decended the order of Hanzhong（HZ, 92. 82%-95. 63%） 〉Aankang（AK, 81.15%-81.97%） 〉Qionglai（QL, 60.6%4-62.19%） 〉Yongji（YJ, 51.38%-53.41%）. There was no significant difference in V（Ⅴ） reduction process between the two V（Ⅴ） concentration treatments. With Fe（Ⅲ） and V（Ⅴ） as coexistent electron acceptor, the addition of Fe（Ⅲ） prolonged the initial V（Ⅴ） reduction time to 15-20 d of incubation and decreased V（Ⅴ） reduction rate to 66.50%-75.26% with microbes from HZ, 67.15%-69.22% with microbes from AK, 48.14%-48.72% with microbes from YJ and 0-11.80% with microbes from QL, respectively. Fe（Ⅲ） reduction rate for each treatment was almost 100% when Fe（ Ⅲ） and V（Ⅴ） coexisted. The maximun Fe（ Ⅲ ） reduction rate（Vmax） was in the order of AK 〉HZ 〉QL 〉YJ. The increase of V（Ⅴ） addition resulted in an increase in Vmax and a decline in the time corresponding toVmax（Zvmax） with microbes from AK, HZ and YJ, while opposite with microbes from QL. The synergistic effect between V（Ⅴ） reduction and Fe（Ⅲ） reduction with microbes from AK, HZ and YJ probably could be explained by the considerable contribution of facultative red

关 键 词：微生物Fe(Ⅲ)还原 V(V)还原 水稻土 厌氧培养 

分 类 号：X53[环境科学与工程—环境工程]