If you go off of weight alone, plants are by far the most prevalent life form on the planet, making up greater than 80% of the total biomass on Earth. This is intuitive as trees are known for being very heavy. What is less intuitive is that the second most prevalent form of life on the planet is bacteria, making up around 80% of all non-plant biomass on the planet. When most people think about bacteria, we tend to associate them with disease. In recent days, talk of probiotics and fermentation has slightly shifted people’s views of bacteria to a more positive light. That said, the scope of bacterial roles in ecosystems is not commonly comprehended, especially given their clear hyper prevalence on this Earth.
It is difficult to quantify the cumulative environmental impact of microbes due to the enormous diversity of microbe species. It is clear, however, that microbes are vital due to their key roles in nutrient cycling, soil health, and plant-microbe interactions. Soil microbes in particular are responsible for driving various biologic transformations that convert soil organic matter into readily available pools of micro and macro nutrients. Various soil bacteria form complicated metabolic relationships with plants that contribute greatly to the stress resistance of the plants and their ability to uptake nutrients from the soil. Due to the extensive supporting role that microorganisms play in every ecosystem, climate impacts on their populations have the potential to destabilize and destroy ecosystems as well as cripple agricultural production from the bottom up.
Due to the complex interactions that occur between abiotic and biotic environmental factors, it is a huge challenge to accurately predict how climate change will shape life on our planet in coming years. This uncertainty poses a real threat to human life as our existence is intrinsically linked to the health of the ecosystems that we interact with and exist within. Due to the prevalence of bacteria and their significance in ecosystems, understanding how different environmental conditions can contribute to stress on their populations is an important area of research for predicting climate change outcomes. While effects of drought and heatwaves on bacteria have been studied, little research has been done on how chemical conditions can affect climate stress in bacteria.
The 2021 paper The Division Defect of a Bacillus subtilis minD noc Double Mutant Can Be Suppressed by Spx-Dependent and Spx-Independent Mechanisms by Yu et al. identified that genetically weakened soil bacteria, die when exposed to high temperatures. This paper reasonably assumed that temperature was the sole stressor aside from the genetic factors which affected the survival of the bacterium. Un-published research found that the specific media (think bacteria food) which the bacteria was grown on could be altered in order to allow the bacteria to survive, implying that the chemical conditions that the bacteria grew on contributes in some way to the death of these stressed soil bacteria at high temperatures.
In order to better understand this unforeseen interaction, I used a different media that resulted in the death of the same genetically stressed soil bacteria at high temperature and a process known as transposon mutagenesis. Transposon mutagenesis allows you to find specific genetic mutations, known as suppressors, that allow bacteria to survive in conditions that they cannot otherwise survive in. By identifying which genes can be mutated in order to allow survival of these genetically stressed soil bacteria at high temperatures, the mechanism of lethality can be better speculated at and understood. My assumption in undertaking this process was that the same suppressors would be identified in my study as were identified in the Yu et al. study, which would imply that the same chemical and temperature interaction was causing the cells to die on both forms of media.
Unfortunately, the suppressors that were identified in my study and the suppressors that were identified in the Yu et al. study were almost entirely different. This difference demonstrates that a different chemical interaction was causing death at high temperatures on the two separate types of media. This finding opens the door for future research as it establishes the climate change outcomes for bacteria in chemically different environmental conditions can be greatly different.
Due to the environmental significance of various soil bacteria, it is incredibly important to be able to predict how increasing environmental temperatures will affect their populations in various ecosystems. In order to best manage impacts on humans caused by climate change, this will likely become a more important area of climate change research. Climate change is a severe threat to human quality of life. It is necessary to do all that we can while we can to make preparations for the changes that ecosystems will go through.
Seth Heatwole is a senior at the O’Neill School of Public and Environmental Affairs.
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