2004-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/709897摘要：地質紀錄中的硫同位素成份，一直被視為一項優秀的微生物活動指標，能夠同時反應古老大氣和海洋化學成分。微生物參與的硫同位素分化，則是低溫地球化學環境中，唯一可以造成大量同位素分化的作用，並且能夠穩定存留在地質紀錄中，是偵測生命活動靈敏度很高的工具。嗜硫微生物控制著海洋沉積物中含硫化合物的氧化還原反應，藉由硫同位素成分所提供的訊息，可以解析海洋環境中硫循環的種種現象與過程。然而，嗜硫菌種的硫同位素分化研究十分有限，少數關於分化係數的研究，都是探討菌種在其最適生長條件之下的反應，至於環境因子變異對分化係數的影響，不僅只研究過幾個容易培養的菌種，截至目前為止也沒有任何定量化的模式，足以用來推測硫同位素分化和地質環境之間的關聯。 本研究計畫系統性的探討嗜硫菌種之硫同位素分化效應，運用菌種培養技術，在實驗室中控制嗜硫菌種生長條件與各項參數，嘗試了解不同生長條件對於微生物硫同位素分化程度所產生的影響。經由硫同位素分化係數的測定，並配合地球化學與多重硫同位素分析，同時解析微生物參與的動力分化反應所造成多重同位素分化效應，進而解釋海洋之硫同位素分化演化與嗜硫微生物之生理作用和地球環境變化之間的關聯。 <br> Abstract: Sulfur isotopic compositions have been demonstrated as excellent biomarkers of microbial life and unique proxies of ancient atmospheric and oceanic chemistry. As a biomarker, sulfur isotopes offer a distinctive and durable record of microbial activities and enhance the sensitivity of life detection. Sulfur oxidation and reduction are controlled by sulfur utilizing microorganisms in marine sediments. Understanding of microbial sulfur isotope fractionation provides useful information for sulfur cycling in marine environment. The interpretation of the sulfur isotopic fractionations for marine sulfide and sulfate deposits relies significantly on results from the studies of microbial batch experiments. Available data of fractionation factors, however, are limited. Most experiments for microbial sulfur isotope fractionations were generally conducted with pure cultures or natural populations incubated under optimized growth conditions. They didn’t cover a wide range of diverse genera or species, nor investigate microbial systems under limited or dynamic conditions. The mechanism and growth conditions governing microbial sulfur isotope fractionations are still under debate. There is no quantitative model to descript the relationship between microbial sulfur isotope fractionation and growth condition so far. The sulfur isotopic systematics unraveled from laboratory experiments can provide valuable information to address the question of the sulfur cycling and evolution in marine environment. This study will apply cultivation techniques to correlate microbial sulfur isotope fractionations with various growth conditions, such as temperature, pH, and nutrition. Multiple sulfur isotope analysis with a capability for nanomole samples and highly spacial-resolution will be a powerful tool to unravel the sulfur metabolisms in the laboratory experiments, modern natural settings and the ancient environments. The aim of this study is to look for a promising linkage between the sulfur isotope data and environmental factors to interpret the marine sulfur isotope evolution in the Earth history.硫同位素分化嗜硫微生物多重硫同位素分析sulfur isotope fractionationsulfur utilizing microorganismsmultiple sulfur isotope analysis