Phenazine-1-carboxylic acid (PCA) is a broad-spectrum antibiotic produced by rhizobacteria in the dryland wheat fields of the Columbia Plateau. PCA and other phenazines reductively dissolve Fe and Mn oxyhydroxides in bacterial culture systems, but the impact of PCA upon Fe and Mn cycling in the rhizosphere is unknown. Here, concentrations of dithionite-extractable and poorly crystalline Fe were approximately 10% and 30-40% higher, respectively, in dryland and irrigated rhizospheres inoculated with the PCA-producing (PCA+) strain Pseudomonas synxantha 2-79 than in rhizospheres inoculated with a PCA-deficient mutant. However, rhizosphere concentrations of Fe(II) and Mn did not differ significantly, indicating that PCA-mediated redox transformations of Fe and Mn were transient or were masked by competing processes. Total Fe and Mn uptake into wheat biomass also did not differ significantly, but the PCA+ strain significantly altered Fe translocation into shoots. X-ray absorption near edge spectroscopy revealed an abundance of Fe-bearing oxyhydroxides and phyllosilicates in all rhizospheres. These results indicate that the PCA+ strain enhanced the reactivity and mobility of Fe derived from soil minerals without producing parallel changes in plant Fe uptake. This is the first report that directly links significant alterations of Fe-bearing minerals in the rhizosphere to a single bacterial trait.

中文翻译：

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产生吩嗪-1-羧酸的细菌增强了旱地和灌溉小麦根际中铁矿物质的反应性。

吩嗪-1-羧酸（PCA）是由根瘤菌在哥伦比亚高原旱地麦田中产生的一种广谱抗生素。PCA和其他吩嗪可还原溶解细菌培养系统中的Fe和Mn羟基氧化物，但是PCA对根际中Fe和Mn循环的影响尚不清楚。在这里，在接种PCA的（PCA +）假单胞菌Synxantha 2-79接种的旱地和灌溉根际中，连二亚硫酸盐可萃取的和结晶性较差的Fe的浓度分别比接种α-亚砜的根际中高约10％和30-40％。 PCA缺陷型突变体。但是，根际中Fe（II）和Mn的浓度没有显着差异，表明PCA介导的Fe和Mn的氧化还原转化是瞬时的或被竞争过程所掩盖。小麦生物量中铁和锰的总摄入量也没有显着差异，但PCA +菌株显着改变了铁向芽中的转运。边缘光谱的X射线吸收显示在所有根际中都有大量的含Fe的羟基氧化物和页硅酸盐。这些结果表明，PCA +菌株提高了土壤矿物产生的铁的反应性和迁移率，而不会引起植物对铁的吸收的平行变化。这是第一个直接将根际中含铁矿物的显着变化与单一细菌性状联系起来的报告。这些结果表明，PCA +菌株提高了土壤矿物产生的铁的反应性和迁移率，而不会引起植物对铁的吸收的平行变化。这是第一个直接将根际中含铁矿物的显着变化与单一细菌性状联系起来的报告。这些结果表明，PCA +菌株提高了土壤矿物产生的铁的反应性和迁移率，而不会引起植物对铁的吸收的平行变化。这是第一个直接将根际中含铁矿物的显着变化与单一细菌性状联系起来的报告。