酸性矿山废水（AMD）是生物地球化学循环最活跃地区之一，pH值极低，是研究极端微生物的典型环境。酸性矿山废水特殊生境下的微生物往往具有独特的代谢途径和适应机制，极可能产生结构复杂多样、生物活性广泛的代谢产物，是嗜酸酶的重要来源，且在基因资源的开发和应用方面具有独特优势。目前从该环境中分离嗜酸酶的研究主要基于纯培养技术，大量未培养微生物中的嗜酸酶尚未得到充分挖掘和鉴定。β‑甘露聚糖酶是能水解甘露聚糖的工业酶，其中嗜酸β‑甘露聚糖的应用最为广泛，但是目前少有对β-甘露聚糖酶嗜酸机理的研究。本项目拟耦合宏基因组文库构建和宏基因组测序挖掘酸性矿坑水中的β-甘露聚糖酶基因，对酶基因进行异源表达和酶学特性分析，结合生物信息学、突变和同源建模等方法解析嗜酸β-甘露聚糖酶的酸适应机制。其研究成果不仅可为相关糖苷水解酶的酸碱性质改造提供指导，而且对极端生境中酶资源的挖掘与利用有重要的借鉴意义。

Acid Mine Drainages (AMD) are typically featured by extreme acidity and high concentrations of toxic metals and sulfate, and they represent an extreme environment for microorganisms. These acidophilic microorganisms have unique gene types, special physiological mechanisms and metabolites, which provide important sources for extracting acidophilic enzymes. Only few enzymes have been identified from AMD by traditional isolation and culture methods, while a large portion of uncultured microorganisms thrived in AMD are uncharacterized. Endo-β-mannanases are industrial glycoside hydrolases that randomly cleave the β-1,4-linkage in mannans. Acidophilic β-mannanases were the most widely applied but there is few research on the acidophilic mechanisms of them. In this research, function/sequence-based screening of an AMD-derived metagenomic library and high-throughput metagenome sequencing were combined to screen acidophilic β-mannanases. Genes encoding β-mannanase were cloned and expressed in Escherichia Coli or Pichia Pastoris, as well as their biochemical characterizations were analyzed. Finally, bioinformatic, mutational and homology model studies were carried out to elucidate the acid adaptation mechanisms of acidophilic β-mannanases. This study may provide a novel strategy to modify the acid and/or alkali properties of the related glycosidases, and also provide valuable experiences of exploitation acidophilic enzymes from extreme environments.