College of Forestry and Co-Innovation Center for Sustainable Forestry in Southern China, Jiangsu Key Laboratory for Prevention and Management of Invasive Species, Nanjing Forestry University, Nanjing, Jiangsu, China.
Appl Environ Microbiol. 2023 May 31;89(5):e0203422. doi: 10.1128/aem.02034-22. Epub 2023 May 8.
Potassium feldspar (KO·AlO·6SiO) is considered to be the most important source of potash fertilizer. The use of microorganisms to dissolve potassium feldspar is a low-cost and environmentally friendly method. Priestia aryabhattai SK1-7 is a strain with a strong ability to dissolve potassium feldspar; it showed a faster pH drop and produced more acid in the medium with potassium feldspar as the insoluble potassium source than in the medium with KHPO as the soluble potassium source. We speculated whether the cause of acid production was related to one or more stresses, such as mineral-induced generation of reactive oxygen species (ROS), the presence of aluminum in potassium feldspar, and cell membrane damage due to friction between SK1-7 and potassium feldspar, and analyzed it by transcriptome. The results revealed that the expression of the genes related to pyruvate metabolism, the two-component system, DNA repair, and oxidative stress pathways in strain SK1-7 was significantly upregulated in potassium feldspar medium. The subsequent validation experiments revealed that ROS were the stress faced by strain SK1-7 when interacting with potassium feldspar and led to a decrease in the total fatty acid content of SK1-7. In the face of ROS stress, strain SK1-7 upregulated the expression of the gene, allowing malic enzyme (ME2) to produce more pyruvate to be secreted outside the cell using malate as a substrate. Pyruvate is both a scavenger of external ROS and a gas pedal of dissolved potassium feldspar. Mineral-microbe interactions play important roles in the biogeochemical cycling of elements. Manipulating mineral-microbe interactions and optimizing the consequences of such interactions can be used to benefit society. It is necessary to explore the black hole of the mechanism of interaction between the two. In this study, it is revealed that SK1-7 faces mineral-induced ROS stress by upregulating a series of antioxidant genes as a passive defense, while overexpression of malic enzyme (ME2) secretes pyruvate to scavenge ROS as well as to increase feldspar dissolution, releasing K, Al, and Si into the medium. Our research provides a theoretical basis for improving the ability of microorganisms to weather minerals through genetic manipulation in the future.
钾长石（KO·AlO·6SiO）被认为是最重要的钾肥来源。利用微生物溶解钾长石是一种低成本且环保的方法。 Priestia aryabhattai SK1-7 是一种具有很强溶解钾长石能力的菌株；与以 KHPO 为可溶钾源的培养基相比，它在以钾长石为不可溶钾源的培养基中表现出更快的 pH 值下降和产生更多的酸。我们推测产酸的原因是否与一种或多种应激有关，例如矿物诱导产生活性氧（ROS）、钾长石中的铝以及由于 SK1-7 与钾长石之间的摩擦对细胞膜造成的损伤，并通过转录组进行了分析。结果表明，在钾长石培养基中，菌株 SK1-7 中与丙酮酸代谢、双组分系统、DNA 修复和氧化应激途径相关的基因表达显著上调。随后的验证实验表明，ROS 是 SK1-7 与钾长石相互作用时面临的应激，并导致 SK1-7 的总脂肪酸含量下降。在面对 ROS 应激时，菌株 SK1-7 上调了基因的表达，使苹果酸酶（ME2）能够利用苹果酸作为底物产生更多的丙酮酸并将其分泌到细胞外。丙酮酸既是外部 ROS 的清除剂，也是溶解钾长石的油门。 矿物-微生物相互作用在元素的生物地球化学循环中起着重要作用。操纵矿物-微生物相互作用并优化这种相互作用的后果，可以造福社会。有必要探索两者相互作用机制的黑洞。在这项研究中，揭示了菌株 SK1-7 通过上调一系列抗氧化基因作为被动防御来应对矿物诱导的 ROS 应激，而过量表达的苹果酸酶（ME2）则分泌丙酮酸来清除 ROS 并增加长石的溶解，将 K、Al 和 Si 释放到培养基中。我们的研究为未来通过遗传操作提高微生物风化矿物的能力提供了理论依据。
