LExEN: Life in Acid

9978205 banfield不寻常的微生物在高温、极酸的溶液中茁壮成长，这些溶液与风化的富含黄铁矿的岩石有关。先前的工作已经记录了在30 - 50摄氏度，pH 0 - 1.0溶液中的动态古细菌，细菌和真核生物群落。黄铁矿中的还原铁和硫是重要的微生物能源。催化Fe2+氧化的微生物显著影响硫酸的生成速率。石养生物和异养生物的种群随温度、溶液组成、pH值和位置而变化。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，并确定特定的酸和离子强度抵抗和能量产生机制，使微生物群落能够在极酸性环境中生存。一般来说，对大多数极端亲酸微生物群落成员的身份和生存策略知之甚少。一种新的中温热铁氧化古细菌（嗜酸铁单胞菌）已从加利福尼亚州铁山的一个野外地点分离出来。其他物种将从已知含有很少研究的氧化铁酸微生物和以前认识的新亲戚“氧化铁钩端螺旋体”的样品中分离出来。分离株将用于生化研究。这一地区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，将探讨细胞壁组成（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。先前的研究表明，除了氧化亚铁硫杆菌（Thiobacillus ferrooxidans）使用的锈青素外，细胞色素对细菌和古细菌的铁氧化也很重要。将确定相关的细胞色素，以评估支撑生态系统的能量产生机制的多样性。

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.