Link between capacity for current production and syntrophic growth in Geobacter species.
Link between capacity for current production and syntrophic growth in Geobacter species.
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DOI：
10.3389/fmicb.2015.00744
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发表时间：
2015
影响因子：
5.2
通讯作者：
Lovley DR
中科院分区：
文献类型：
--
作者：
Rotaru AE;Woodard TL;Nevin KP;Lovley DR
电极是非天然的电子受体，目前尚不清楚一些地杆菌属物种如何进化为使用电极作为末端电子受体。对不同地杆菌属物种的分析表明，它们当前的生产能力各不相同。金属还原地杆菌和嗜氢地杆菌产生高电流密度（约 0.2 mA/cm2），与硫还原地杆菌相当。 G. bremensis、G. chapellei、G. humireducens 和 G. uraniireducens 产生的电流要低得多（约 0.05 mA/cm2），而 G. bemidjiensis 之前被发现不产生电流。当前发电的有效性与 Fe(III) 氧化物还原率之间没有对应关系。一些高电流密度菌株（G. metallireducens 和 G. Hydronophilus）还原 Fe(III) 氧化物的速度与一些低电流密度菌株（G. bremensis、G. humireducens 和 G. uraniireducens）一样快，而其他低电流密度菌株（G. bemidjiensis 和 G. chapellei）还原 Fe(III) 氧化物的速度与高电流密度菌株 G.sulfurreducens 一样慢。然而，产生更高电流的能力和互养生长的能力之间存在对应关系。研究发现，嗜氢芽孢杆菌可以与巴氏甲烷八叠球菌共培养，巴氏甲烷八叠球菌能够直接进行种间电子转移（DIET），但不能与仅能够进行氢气或甲酸转移的亨加特甲烷螺菌共培养。导电颗粒活性炭 (GAC) 刺激嗜氢芽胞杆菌 - 巴克氏杆菌共培养物的新陈代谢，与通过 DIET 进行的电子交换一致。这些发现，加上之前发现的 G. metallireducens 和 G.硫还原菌也能够进行 DIET，表明优化 DIET 的进化偶然地赋予了一些地杆菌属物种产生高密度电流的能力。
Electrodes are unnatural electron acceptors, and it is yet unknown how some Geobacter species evolved to use electrodes as terminal electron acceptors. Analysis of different Geobacter species revealed that they varied in their capacity for current production. Geobacter metallireducens and G. hydrogenophilus generated high current densities (ca. 0.2 mA/cm2), comparable to G. sulfurreducens. G. bremensis, G. chapellei, G. humireducens, and G. uraniireducens, produced much lower currents (ca. 0.05 mA/cm2) and G. bemidjiensis was previously found to not produce current. There was no correspondence between the effectiveness of current generation and Fe(III) oxide reduction rates. Some high-current-density strains (G. metallireducens and G. hydrogenophilus) reduced Fe(III)-oxides as fast as some low-current-density strains (G. bremensis, G. humireducens, and G. uraniireducens) whereas other low-current-density strains (G. bemidjiensis and G. chapellei) reduced Fe(III) oxide as slowly as G. sulfurreducens, a high-current-density strain. However, there was a correspondence between the ability to produce higher currents and the ability to grow syntrophically. G. hydrogenophilus was found to grow in co-culture with Methanosarcina barkeri, which is capable of direct interspecies electron transfer (DIET), but not with Methanospirillum hungatei capable only of H2 or formate transfer. Conductive granular activated carbon (GAC) stimulated metabolism of the G. hydrogenophilus – M. barkeri co-culture, consistent with electron exchange via DIET. These findings, coupled with the previous finding that G. metallireducens and G. sulfurreducens are also capable of DIET, suggest that evolution to optimize DIET has fortuitously conferred the capability for high-density current production to some Geobacter species.