The temperature limit that bacteria can tolerate has long been a topic of debate. Bacteria have been discovered in hot spring waters at 90°C, while no microorganisms have been found in even slightly higher temperatures. As a result, most experts believe that the upper limit for bacterial heat resistance is 90°C. The vast majority of microorganisms perish below this temperature, which is why boiling water is generally effective for sterilization.
However, this raises the question: can life on Earth exist beyond the 90°C threshold?
In 1983, researchers discovered a heat-resistant bacterium in a hydrothermal vent at the entrance to the California Bay. The two biologists who found this new bacterium recorded a water temperature of 250°C, leaving them astonished that life could exist at such extreme temperatures.
It is well-known that water boils and turns to steam at 100°C under normal atmospheric pressure. The hot springs originating from underwater volcanoes are located 2,600 meters beneath the ocean surface, where the pressure reaches 265 atmospheres, creating an unusual environment of high-temperature water.
To study these heat-resistant bacteria, scientists employed special methods to cultivate them artificially. They constructed a complete set of equipment made of titanium that could withstand high temperatures and pressures, simulating the conditions of the ocean floor. Through extensive chemical analysis, scientists found that the DNA structure of these bacteria was quite unusual, theoretically allowing them to survive only in water not exceeding 120°C. This suggests that these heat-resistant bacteria must possess other unknown characteristics.
Further exploration revealed that the proteins of these bacteria contained certain unique types of amino acids that had never been found in any other organisms. These amino acids featured extra stabilizing chemical bonds, giving the proteins exceptional strength. Additionally, branched chemical bonds were discovered in their lipid compounds, enabling the bacteria to withstand the intense impact of high-temperature molecules.
Moreover, scientists believe that the adaptation of heat-resistant bacteria to their environment must be multifaceted, involving biological and chemical factors. It was later discovered that sulfur plays a significant role in the metabolism of these bacteria.
The discovery of heat-resistant bacteria has caused a stir in the scientific community, prompting experts to reevaluate various biological questions, such as the origin of life. Perhaps life on Earth did not emerge after the planet cooled, as previously thought. Traditional views held that temperatures exceeding 100-120°C could not support life, but these perspectives now seem in need of revision.
