College of Life Sciences, Nanjing Agricultural Universitygrid.27871.3b, Key Laboratory of Agricultural and Environmental Microbiology, Ministry of Agriculture, Nanjing, China.
College of Biological and Food Engineering, Anhui Polytechnic University, Wuhu, China.
Appl Environ Microbiol. 2021 Nov 24;87(24):e0155221. doi: 10.1128/AEM.01552-21. Epub 2021 Sep 29.
Silicate mineral weathering (dissolution) plays important roles in soil formation and global biogeochemical cycling. In this study, a combination of genomics, transcriptomics, and genetics was used to identify the molecular basis of mineral weathering activity and acid tolerance in Pseudomonas azotoformans F77. Biotite was chosen as a silicate mineral to investigate mineral weathering. The genome of strain F77 was sequenced, and the genes significantly upregulated when grown in the presence of biotite included mineral weathering-related genes associated with gluconic acid metabolism, flagellar assembly, and pilus biosynthesis and acid tolerance-related genes associated with neutralizing component production, reducing power, and proton efflux. The biotite-weathering behaviors of strain F77 and its mutants that were created by deleting the , , and genes, which are involved in gluconic acid metabolism, and the , , and genes, which are involved in acid tolerance, were determined. The Fe and Al concentrations in the strain F77-inoculated medium increased 2.2- to 13.7-fold compared to the controls. The cell numbers of strain F77 increased over time, while the pH values in the medium ranged from 3.75 to 3.90 between 20 and 36 h of incubation. The release of Al and Fe was significantly reduced in the F77 Δ, F77 Δ, F77 Δ, and F77 Δ mutants. Bacterial growth was significantly reduced in the presence of biotite in the F77 Δ and F77 Δ mutants. Our results demonstrated the acid tolerance of strain F77 and suggested that multiple genes and metabolic pathways in strain F77 are involved in biotite weathering and acid tolerance during the mineral weathering process. Acid production and tolerance play important roles in effective and persistent mineral weathering in bacteria, although the molecular mechanisms governing acid production and acid tolerance in bacteria have not been fully elucidated. In this study, the molecular mechanisms underlying biotite (as a silicate mineral) weathering (dissolution) and acid tolerance of F77 were characterized using genomics, transcriptomics, and genetics analyses. Our results showed that the genes and metabolic pathways for gluconic acid metabolism, flagellar assembly, and pilus biosynthesis may play important roles in mineral weathering by strain F77. Notably, the genes associated with neutralizing component production, reducing power, and proton efflux may be related to acid tolerance in strain F77. The expression of these acid production- and acid tolerance-related genes was observed to be increased by biotite in strain F77. Our findings may help to elucidate the molecular mechanisms governing mineral weathering and, especially, acid tolerance in mineral-weathering bacteria.
硅酸盐矿物风化（溶解）在土壤形成和全球生物地球化学循环中起着重要作用。在这项研究中，综合使用基因组学、转录组学和遗传学来鉴定 Pseudomonas azotoformans F77 中矿物风化活性和耐酸的分子基础。选择黑云母作为硅酸盐矿物来研究矿物风化。对菌株 F77 的基因组进行了测序，当在黑云母存在的情况下生长时，显著上调的基因包括与葡萄糖酸代谢、鞭毛组装和菌毛生物合成相关的矿物风化相关基因，以及与中和成分产生、还原力和质子外排相关的耐酸相关基因。确定了 F77 菌株及其突变体的黑云母风化行为，这些突变体通过删除与葡萄糖酸代谢相关的基因 、 、 和 ，以及与耐酸相关的基因 、 、 和 而产生。与对照相比，接种 F77 菌株的培养基中的 Fe 和 Al 浓度增加了 2.2 到 13.7 倍。F77 菌株的细胞数量随着时间的推移而增加，而在 20 到 36 小时的孵育过程中，培养基的 pH 值在 3.75 到 3.90 之间。F77Δ、F77Δ、F77Δ 和 F77Δ 突变体中 Al 和 Fe 的释放明显减少。在黑云母存在的情况下，F77Δ 和 F77Δ 突变体中的细菌生长受到显著抑制。我们的结果证明了 F77 菌株的耐酸性，并表明 F77 菌株中的多个基因和代谢途径参与了在矿物风化过程中的黑云母风化和耐酸。 尽管细菌产酸和耐酸的分子机制尚未完全阐明，但产酸和耐酸在细菌中有效和持续的矿物风化中起着重要作用。在这项研究中，使用基因组学、转录组学和遗传学分析来描述 F77 中黑云母（作为一种硅酸盐矿物）风化（溶解）和耐酸的分子机制。我们的结果表明，与葡萄糖酸代谢、鞭毛组装和菌毛生物合成相关的基因和代谢途径可能在 F77 菌株的矿物风化中起重要作用。值得注意的是，与中和成分产生、还原力和质子外排相关的基因可能与 F77 菌株的耐酸有关。在 F77 中，这些与产酸和耐酸相关的基因的表达观察到被黑云母诱导。我们的发现可能有助于阐明控制矿物风化的分子机制，特别是控制矿物风化细菌耐酸的分子机制。
