Control of ferrous iron oxidation within circumneutral microbial iron mats by cellular activity and autocatalysis
Control of ferrous iron oxidation within circumneutral microbial iron mats by cellular activity and autocatalysis
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DOI：
10.1021/es062203e
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发表时间：
2007-09-01
影响因子：
11.4
通讯作者：
Emerson, David
中科院分区：
文献类型：
--
作者：
Rentz, Jeremy A.;Kraiya, Charoenkwan;Emerson, David
研究了微生物铁垫样品对亚铁离子（Fe 2+）的氧化作用，铁垫样品主要由铁锈盖菌（Gallionella ferrugulosa）的螺旋柄或赭色纤发菌（Leptothrix ochracea）的鞘组成。微生物垫样品的伪一级速率常数范围为0.029 +/- 0.004至0.249 +/- 0.042 min（-1），与铁含量相关性良好（R-2 = 0.929）。叠氮化钠处理（1 mM）样品的速率常数估计由氧化铁茎或鞘的自催化氧化，其值范围为0.016 +/- 0.008至0.062 +/- 0.006 min（-1）。由于细胞活动导致的Fe 2+氧化在采样位置和采样时间方面是可变的，速率常数为0.013 +/- 0.005至0.187 +/- 0.037 min（-1）。细胞过程和自催化的氧化速率具有相同的数量级，这表明利用Fe 2+作为能源的细菌与它们自己的副产品竞争生长，而不是化学氧化（在水氧浓度低于饱和的条件下）。在本研究中使用循环伏安法同时测量Fell和氧气，可以收集统计学上有意义和可重复的数据，这两个因素限制了有氧、环中性、Fe 2+氧化速率研究。
Ferrous iron (Fe2+) oxidation by microbial iron mat samples, dominated by helical stalks of Gallionella ferruginea or sheaths of Leptothrix ochracea, was examined. Pseudo-first-order rate constants for the microbial mat samples ranged from 0.029 +/- 0.004 to 0.249 +/- 0.042 min(-1) and correlated well with iron content (R-2 = 0.929). Rate constants for Na azide-treated (1 mM) samples estimated autocatalytic oxidation by iron oxide stalks or sheaths, with values ranging from 0.016 +/- 0.008 to 0.062 +/- 0.006 min(-1). Fe2+ oxidation attributable to cellular activities was variable with respect to sampling location and sampling time, with rate constants from 0.013 +/- 0.005 to 0.187 +/- 0.037 min(-1). Rates of oxidation of the same order of magnitude for cellular processes and autocatalysis suggested that bacteria harnessing Fe2+ as an energy source compete with their own byproducts for growth, not chemical oxidation (under conditions where aqueous oxygen concentrations are less than saturating). The use of cyclic voltammetry within this study for the simultaneous measurement of Fell and oxygen allowed the collection of statistically meaningful and reproducible data, two factors that have limited aerobic, circumneutral, Fe2+-oxidation rate studies.