PioABC-Dependent Fe(II) Oxidation during Photoheterotrophic Growth on an Oxidized Carbon Substrate Increases Growth Yield.
PioABC-Dependent Fe(II) Oxidation during Photoheterotrophic Growth on an Oxidized Carbon Substrate Increases Growth Yield.
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在氧化碳基质上光异养生长期间，PioABC 依赖性 Fe(II) 氧化可提高生长产量。
DOI：
10.1128/aem.00974-22
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发表时间：
2022
影响因子：
4.4
通讯作者：
Fixen,KathrynR
中科院分区：
文献类型：
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作者：
Haas,NicholasW;Jain,Abhiney;Hying,Zachary;Arif,SabrinaJ;Niehaus,ThomasD;Gralnick,JeffreyA;Fixen,KathrynR
在低氧环境下，进行铁（II）氧化的微生物在铁的生物地球化学循环中起着重要作用。铁（II）氧化已经在自养的背景下进行了大量研究。在这里，我们发现无氧光养菌红假单胞菌（Rhodopseudomonas palustris） CGA010在光异养生长过程中与氧化碳源苹果酸盐一起进行Fe（II）氧化，导致细胞产量增加，并允许更多的碳被定向到细胞生物量。我们通过转录组测序（RNA-seq）探究了这一现象的调控基础，发现已知的npioabcfe （II）氧化基因在palustris中的表达水平取决于氧化还原感应双组分系统RegSR和提供给细胞的碳源的氧化状态。这提供了混合营养生长涉及铁（II）氧化和碳同化产生的还原力的第一个机制证明。细菌同时利用碳和还原性金属（如Fe(II)）被认为在水生环境中很普遍，对这一过程的机制描述可以提高我们对生物地球化学循环的理解。像古红假单胞菌这样的无氧光养细菌通常利用光作为能量，并将有机化合物作为碳源和电子源。当提供富电子化合物如H2、硫代硫酸盐和Fe（II）作为电子供体时，它们也可以利用co2作为碳的二氧化碳固定体。在这里，我们表明，当提供氧化碳化合物苹果酸盐时，Fe（II）氧化可以在另一种情况下用于促进R. palustris的更高生长产量。我们进一步建立了支持这一观察的监管机制。
Microorganisms that carry out Fe(II) oxidation play a major role in biogeochemical cycling of iron in environments with low oxygen. Fe(II) oxidation has been largely studied in the context of autotrophy. Here, we show that the anoxygenic phototroph, Rhodopseudomonas palustris CGA010, carries out Fe(II) oxidation during photoheterotrophic growth with an oxidized carbon source, malate, leading to an increase in cell yield and allowing more carbon to be directed to cell biomass. We probed the regulatory basis for this by transcriptome sequencing (RNA-seq) and found that the expression levels of the knownpioABCFe(II) oxidation genes in R. palustris depended on the redox-sensing two-component system, RegSR, and the oxidation state of the carbon source provided to cells. This provides the first mechanistic demonstration of mixotrophic growth involving reducing power generated from both Fe(II) oxidation and carbon assimilation.IMPORTANCEThe simultaneous use of carbon and reduced metals such as Fe(II) by bacteria is thought to be widespread in aquatic environments, and a mechanistic description of this process could improve our understanding of biogeochemical cycles. Anoxygenic phototrophic bacteria like Rhodopseudomonas palustris typically use light for energy and organic compounds as both a carbon and an electron source. They can also use CO2for carbon by carbon dioxide fixation when electron-rich compounds like H2, thiosulfate, and Fe(II) are provided as electron donors. Here, we show that Fe(II) oxidation can be used in another context to promote higher growth yields of R. palustris when the oxidized carbon compound malate is provided. We further established the regulatory mechanism underpinning this observation.