Genomic factors contributing to the upper temperature growth limits of bacteria

所有生物的生长都有一个温度上限。在整个地球历史上，地球的平均温度发生了几次变化，但目前的气候变化可能是自大约6000万年前发生的古新世-始新世热极大期以来最快的变暖周期之一。地球上的生物将不得不适应这些变化，许多生物将进化出更强的耐热性。在这个提议中，我们研究了细菌使用的一些热适应。在实验室的一系列实验中，我们先前发现的证据表明，细菌用来适应致命温度的一种机制是增加热不稳定蛋白的表达。这是通过改变蛋白质从信使RNA翻译的速率来实现的。另一种推测的机制是，另一种未知的蛋白质，有助于保持热不稳定蛋白的完整性，被大量制造，最终的结果是热不稳定蛋白的半衰期实际上更长。在拟议的研究中，我们将确定增加的蛋白质翻译和其他机制是否在细菌对高温的适应中起重要作用。从拟议的研究中获得的知识将有助于我们理解对温度升高的适应。此外，这些结果将有助于指导生物制造中使用的耐温细菌的实验室进化。重要的是，耐热性通常与对工业生产的化学物质（如酒精）的抵抗力有关，我们的研究可能有助于创造出能够承受更高浓度生物燃料的细菌。

All living organisms have an upper temperature limit to their growth. Throughout earth's history there have been several shifts in its average temperature, but the current climate change may be one of the fastest warming cycles since the Paleocene-Eocene Thermal Maximum which occurred about 60 M years ago. Organisms on earth will have to adapt to these changes, and many will evolve a greater resistance to heat. *** In this proposal we examine some of the heat adaptations that bacteria use. In a laboratory series of experiments we previously found evidence that one mechanism bacteria use to adapt to a lethal temperature is to increase the expression of a thermo-labile protein. This is accomplished by changing the rate that the protein is translated from the messenger RNA. Another presumed mechanism is that another, unknown protein, that helps preserve the integrity of thermo-labile proteins, is made in larger amounts, and the end result is that thermo-labile proteins effectively have longer half-lives. In the proposed research we will determine if increased protein translation and other mechanisms play an important role in the adaptation of bacteria to higher temperatures. *** The knowledge gained from the proposed research will contribute to our understanding of adaptation to warmer temperatures. In addition the results will help guide laboratory-evolution of temperature-resistant bacteria used in bio-manufacturing. Importantly, thermo-resistance often correlates with resistance to industrially-produced chemicals, such as alcohols, and our research may help to create bacteria that can withstand higher concentrations of the bio-fuels that they produce.