LExEN: Life in Acid

9978205异常微生物在高温、极端酸性的溶液中茁壮成长，这些溶液与风化的富含黄铁矿的岩石有关。以前的工作已经记录了在30-50摄氏度、pH 0-1.0的溶液中动态的古生物、细菌和真核生物群落。黄铁矿中还原铁和硫是微生物的主要能源。催化Fe2+氧化的微生物极大地影响着硫酸的生成速度。养石菌和异养菌的数量随着温度、溶液组成、pH和位置的不同而变化。该项目将探索这些种群如何随着地球化学条件的变化而变化，并确定使微生物群落能够在极端酸性环境中生存的特定酸和离子强度、抵抗力和能量产生机制。总体而言，对极端嗜酸微生物群落的大多数成员的身份和生存策略知之甚少。从加利福尼亚州铁山的野外环境中分离到一种新的中温嗜铁氧化古菌(Ferromonas Acadiphilium)。其他物种将从已知含有鲜为人知的氧化亚铁酸杆菌和以前已知的和新的近亲“氧化钩端螺旋体”的样本中分离出来。分离株将用于生化研究。来自该地点的许多生物尚未被鉴定；这些将是进一步测序和分离工作的重点。预计细胞将采用被动的pH抵抗机制(涉及细胞膜成分，可能与S层结合)。因此，将探索细胞壁组成(即脂肪酸和/或蛋白质)对生长条件的依赖性，从而评估可能的抗性机制。先前的工作表明，细胞色素而不是黄曲霉毒素(由氧化亚铁硫杆菌使用)对于细菌和古细菌物种的铁氧化是重要的。将确定相关的细胞色素，以评估支撑生态系统的能源产生机制的多样性。

9978205BanfieldUnusual microorganisms thrive in hot, extremely acidic solutions associated with weathered pyrite-rich rocks. Prior work has documented a dynamic archaeal, bacterial, and eukaryotic community in 30 - 50 degrees C, pH 0 - 1.0 solutions. Reduced iron and sulfur from pyrite are key microbial energy sources. Microbes that catalyze the oxidation of Fe2+ dramatically impact sulfuric acid generation rates. Populations of lithotrophs and heterotrophs vary with temperature, solution composition, pH, and location. This project will explore how these populations change with changes in geochemical conditions and determine the specific acid and ionic strength resistance and energy generation mechanisms that allow microbial communities to exist in extremely acidic environments. In general, little is known about the identity and survival strategies of the majority of members of extremely acidiphilic microbial communities. A novel mesothermophilic iron-oxidizing archaea (Ferromonas acidiphilium) has been isolated from a field site at Iron Mountain, CA. Additional species will be isolated from samples known to contain the little studied Acidomicrobium ferrooxidans and previously recognized and new relatives of "Leptospirillum ferrooxidans". Isolates will be used in biochemical investigations. Many organisms from this site have not been identified; these will be the focus of further sequencing and isolation efforts. It is anticipated that cells will employ passive pH resistance mechanisms (involving cell membrane constituents, possibly in conjunction with S-layers). Thus, the dependence of cell wall composition (i.e., fatty acids and/or proteins) on growth conditions will be explored, and thereby possible resistance mechanisms evaluated. Prior work indicates that cytochromes other than rusticyanin (used by Thiobacillus ferrooxidans) are important for iron oxidation by bacterial and archaeal species. Relevant cytochromes will be identified in order to evaluate the diversity of energy generation mechanisms that underpin the ecosystem.