LEXEN: Strategies of Long-Term Procaryote Survival in Ancient Permafrost Soils

LEXEN：古代永久冻土土壤中原核生物长期生存的策略

• 批准号: 9978271
• 负责人: James Tiedje
• 金额: $ 41.94万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-15 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9978271&HistoricalAwards=false
• 关键词: LEXEN; Strategies; Long; Term; Procaryote

This project is designed to investigate the nature of adaptations associated with soil microbes living in polar soils. Viable microorganisms have been recovered from Siberian Arctic permafrost soil samples having survived for 2 - 3 million years, at low temperatures, and low water activity. Recent results suggest that some of these microbes that have survived are capable of biological activity and growth at subzero temperatures and may be active within the frozen permafrost in some instances. Microbial survival would be expected to accommodate even more stringent requirements in Antarctic permafrost: survival for longer periods-up to 10 million years, at lower temperatures, and low water activity. Using archival samples, the investigators will determine whether the microbes in Arctic and Antarctic permafrost are metabolically active in situ. It is hypothesized that unique organisms are selected under three stresses characteristic of the extreme environment of permafrost (severe cold, low water activity, and age) by molecular and physical adaptations. Compatible solutes and gene/protein expression induced by chilling and freezing will be measured for the purpose of elucidating and comparing the adaptive physiologies of microbes from Arctic and Antarctic permafrost. Adaptations will be correlated with freeze tolerance, protection against damage during prolonged frozen storage and metabolic activity at the lower limits of temperature and water activity. Differential scanning calorimetry will be applied as a means of determining whether intracellular microbial solutions remain unfrozen, crystallize, or vitrify under permafrost conditions.

该项目旨在调查与生活在极地土壤中的土壤微生物有关的适应性的性质。 从西伯利亚北极永久冻土土壤样品中回收了存活的微生物，这些微生物在低温和低水活度下存活了200 - 300万年。 最近的研究结果表明，这些存活下来的微生物中有一些能够在零度以下的温度下进行生物活性和生长，并且在某些情况下可能在冻结的永久冻土中活跃。 微生物的生存将有望适应南极永久冻土层更严格的要求：生存时间更长，可达1000万年，在较低的温度和低水活性。 利用档案样本，研究人员将确定北极和南极永久冻土中的微生物是否在原地代谢活跃。 据推测，独特的生物体被选择在三个应力下的极端环境的永久冻土（严寒，低水分活度，和年龄）的分子和物理适应。 为了阐明和比较北极和南极永久冻土微生物的适应性生理，将测量低温和冷冻诱导的相容性溶质和基因/蛋白质表达。 适应将与耐冻性、在长期冷冻储存期间对损害的保护以及在温度和水活性的下限下的代谢活性相关。 差示扫描量热法将被应用作为一种手段，以确定细胞内的微生物解决方案是否保持解冻，结晶，或玻璃化在冻土条件下。