Bioenergetics in 'Natronanaerobium alkalithermophilum' JW/NM-L6, a member of the anaerobic halo-alkalithermophiles, a novel group of triple extremophiles

该项目的目标是阐明最近分离的新型细菌“嗜碱嗜热钠厌氧菌”菌株JW/NM-L6如何能够在三种极端条件下生长：温度高于50摄氏度，pH值高于8.5，盐浓度超过1.5 M（或10%，wt/vol, NaCl）。这些极端生长条件存在于自然环境中，如日光加热或地热加热的碱性盐湖，也存在于人为环境中（如盐沼、工业废水流）。以前人们认为微生物不能在这种条件下生长。对综合极端生长条件的生理适应很难用常见的生物能量模型来解释。此外，已知的个别极端的适应机制，即高pH值、盐或温度，与这种嗜盐嗜碱热微生物的存在相矛盾，也不能解释。由于这种细菌在广泛的温度、pH值和盐浓度下生长，因此在各种极端组合下生长时，将测量各种生理过程，包括细胞膜上的pH梯度和细胞内溶质组成，以确定使这种细菌能够在这种极端条件下生存的独特性质。这个项目的结果将扩展目前对生命可以茁壮成长的边界的理解，因此将对几个学科产生更广泛的影响。该结果将为研究极端环境条件的适应机制提供一个新的模型，因此对生物化学、微生物学、生物地球化学、生态学、遗传学和各种生物技术领域的科学家很有兴趣。该项目还将涉及美国、新西兰和埃及研究人员之间的合作，并将包括对一名女研究生的培训。

The goal of this project is to elucidate how a recently isolated novel bacterium, 'Natronanaerobium alkalithermophilum' strain JW/NM-L6 is able to grow under combined triple extreme conditions: temperature above 50 degrees centigrade, pH above 8.5, and salt concentrations in excess of 1.5 M (or 10%, wt/vol, NaCl). These extreme growth conditions are found in natural environments such as sunheated or geothermally heated alkaline salt lakes as well as in man-made environments (e.g., salterns, industrial waste streams). Previously it was assumed that microorganisms could not grow under such conditions. Physiological adaptations to the combined extreme growth conditions are difficult to explain with the common bioenergetic models. In addition, known adaptive mechanisms for individual extremes, i.e. high pH, salt or temperature alone, contradict and do not explain the existence of this halophilic alkalithermophile. Since this bacterium grows under a wide range of temperatures, pH values and salt concentration, various physiological processes, including the pH gradient across the cell membrane and intracellular solute composition will be measured when grown under various combinations of extremes to identify the unique properties which enable this bacterium to live under such extreme conditions. The results of this project will extend the present understanding of the boundaries under which life can thrive and thus will have a broader impact on several disciplines. The results will provide a novel model for the study of adaptive mechanisms to extreme environmental conditions and thus is of interest to scientists in the fields of biochemistry, microbiology, biogeochemistry, ecology, genetics, and various areas of biotechnology. This project will also involve collaboration between U.S., New Zealand and Egyptian researchers, and will include training for a female graduate student.