Pseudomonas azotoformans F77和Pseudomonas paracarnis P1风化黑云母的效应及机制比较

Distinct biotite weathering effects and mechanisms of Pseudomonas azotoformans F77 and Pseudomonas paracarnis P1

摘要:

【目的】比较高效矿物风化固氮假单胞菌(Pseudomonas azotoformans) F77及其亲缘关系较近的假单胞菌(Pseudomonas paracarnis) P1风化黑云母的效应和机制。【方法】通过检测两株菌在不同时间点的发酵液中细胞数量、pH值、葡萄糖剩余量、葡萄糖酸浓度和可溶性Fe、Al释放量，比较它们对黑云母的风化效果与生理机制。采用RNA-seq技术研究这两株菌风化黑云母过程中出现差异的分子机制。【结果】在持续5 d的风化试验中，菌株F77发酵液中的细胞数量和pH值低于菌株P1，葡萄糖酸浓度是菌株P1的27.3-53.9倍，Fe和Al元素的释放量是菌株P1的3.3-23.3倍。比较转录组数据表明，菌株F77特有的基因数量(2 872)和差异基因数量(1 832)均多于菌株P1 (分别为1 903和1 258)。菌株F77在胞内物质跨膜转运与碳代谢、细胞运动、趋化与信号诱导等途径中基因数量也高于菌株P1。此外，菌株F77的超氧化物歧化酶和过氧化氢酶基因差异表达倍数、葡萄糖酸合成基因数量和差异表达倍数也明显高于菌株P1。【结论】菌株F77风化黑云母以及合成葡萄糖酸的能力显著高于菌株P1。菌株F77通过产生葡萄糖酸来促进黑云母的风化。添加黑云母显著促进了菌株F77胞内与矿物风化相关基因的表达，如物质跨膜转运、细胞运动与趋化、信号诱导、碳代谢及能量代谢等途径基因。此外，葡萄糖酸合成途径基因、超氧化物歧化酶基因以及过氧化氢酶基因在矿物风化中可能发挥重要作用。

Abstract:

[Objective] To compare the biotite weathering activities and mechanisms between Pseudomonas azotoformans F77 and Pseudomonas paracarnis P1. [Methods] During the mineral weathering process, the dissolved Fe and Al concentrations, cell number, pH, gluconic acid concentration, and residual glucose concentration in the culture medium were determined to reveal the biotite weathering effects and mechanisms of strains F77 and P1. Furthermore, RNA-seq was employed to explore the molecular mechanism for the difference in the biotite weathering effect between the two strains. [Results] During the 5 days of mineral weathering, strain F77 increased Fe and Al concentrations by 3.3-23.3 folds and gluconic acid concentration by 27.3-53.9 folds the compared with strain P1. Meanwhile, strain F77 showed decreased cell number and medium pH compared with strain P1. The data of comparative transcriptomics showed that strain F77 had more specific genes (2 872) and differentially expressed genes (1 832) than strain P1 (1 903 and 1 258 genes, respectively). Additionally, strain F77 carried more genes involved in the membrane transport, carbohydrate metabolism, cell motility, chemotaxis, and signal transduction than strain P1. Furthermore, strain F77 had higher fold changes in the expression levels of superoxide dismutase and catalase genes as well as higher number and fold changes of the genes involved in gluconic acid synthesis than strain P1. [Conclusion] Strain F77 surpassed strain P1 in weathering the biotite and producing gluconic acid. Strain F77 promoted the biotite weathering by producing gluconic acid. The addition of biotite significantly up-regulated the expression of genes involved in the transmembrane transport, cell movement and chemotaxis, signal induction, and carbon and energy metabolisms in mineral weathering. Furthermore, the genes involved in gluconic acid synthesis and encoding superoxide dismutase and catalase may play a role in the mineral weathering by strain F77.