基于比较基因组学和蛋白质组学探究浸矿微生物Acidithiobacillus ferrivorans 抗寒耐酸的分子机理

Psychrotolerant acidophiles are important bioleaching microorganisms, but the molecular mechanisms of their cold and acid tolerance and the bioleaching mechanism are not well understood. This has hindered the development of biohydrometallurgy technology at low temperature. This project takes the typical psychrotolerant acidophile Acidithiobacillus ferrivorans YL15 as an research object. The main research includes three parts: “comparative genomics analysis of Acidithiobacillus ferrivorans”, “the comparative proteomics analysis of Acidithiobacillus ferrivorans under cold and acid stresses”, and “the expression of key functional genes during bioleaching of pyrite at low temperature“. At first, the physiological and biochemical properties of Acidithiobacillus ferrivorans are analyzed and comparative genomics analysis is carried out between the species and its phylogenetic neighbors. After bioinformatics comparison, some genes with important biological functions would be found. After that, the comparative proteomics analysis is performed to understand the adaptation mechanism of Acidithiobacillus ferrivorans under the cold and acid dual stresses. This would lead to the discovery of some key functional proteins with respect to the cold and acid tolerance and even their molecular regulation network. Finally, the differential expression of key function genes during bioleaching of pyrite at low temperature and the dissolution of mineral as well as its rate-limit step are explored. These would clarify the correlative mechanism among the cold and acid dual stresses, expression of critical functional genes and the metal extraction rate during bioleaching at low temperature. All the results would provide some theoretical guidance for the clarification of bioleaching mechanism at low temperature.

耐冷嗜酸菌是一类重要的浸矿微生物，但目前关于耐冷嗜酸菌的环境适应机制及其浸矿机理尚未明确，限制了低温生物浸矿技术的发展。本项目以耐冷嗜酸菌Acidithiobacillus ferrivorans YL15为研究对象，围绕“菌种比较基因组学分析”、“菌种比较蛋白质组学分析”和“低温生物浸矿”三个方面展开研究。首先确定菌种的最适生长参数，并将该菌与其近缘物种的全基因组进行比较，通过生物信息学比对，初步挖掘菌种具有重要生物学功能的基因；此后，采用比较蛋白质组学技术探讨寒冷和酸双重胁迫下菌种显著差异表达的蛋白，揭示菌种抗寒耐酸的关键功能基因及其分子调控网络；最后，探明黄铁矿低温生物浸出过程中菌种关键功能基因的差异表达情况，并考察矿物氧化溶解反应及其限速步骤。通过以上研究，查明寒冷和酸双重胁迫—关键功能基因差异表达—金属浸出效率三者之间的关联机制，为低温生物浸矿机理的阐明提供理论指导。

耐冷嗜酸菌在硫化矿物低温生物浸出过程中扮演着关键角色，但其抗寒耐酸机制及低温浸矿机理仍然不清楚，限制了低温生物浸矿技术的发展。基于此，本项目以典型耐冷嗜酸菌Acidithiobacillus ferrivorans为研究对象，首先探究了自主分离的Acidithiobacillus ferrivorans菌株YL15在不同pH和温度下的生长特性，确定其最适生长pH为2.2。研究了低温浸出黄铜矿的机制，发现YL15在6℃能促进黄铜矿的溶浸，并且减少钝化物的产生。比较了Acidithiobacillus ferrivorans及其近缘物种的基因组，发现Acidithiobacillus ferrivorans具有一系列特有基因，这些基因涉及能量代谢、氨基酸代谢、信号转导、膜运输等途径，可能与A.ferrivorans适应复杂的外部环境有关。采用基于TMT的比较蛋白质组学进一步挖掘YL15冷适应和耐酸的相关蛋白，发现与细胞运动和趋化、细胞膜、生物大分子定位、双组分系统、生物膜形成相关蛋白的表达同时在低温和低pH下显著上调，而在低温和低pH双重胁迫下，一些蛋白如碳代谢、核苷酸代谢相关的蛋白表达水平则会下调。推测Acidithiobacillus ferrivorans通过这些通路蛋白的上调/下调，以此来适应低温和低pH环境。通过该项目的研究，发现了与耐冷嗜酸菌适应低温、低pH的关键通路和关键基因（蛋白），揭示了Acidithiobacillus ferrivorans抗寒耐酸的分子机制和黄铜矿低温生物溶浸机理，可为低温浸矿提供参考。