Climate Fighting Bacteria

The Global Climate Strike on March 25 once again brought the issue of global warming into the spotlight for good reason: climate change is a significant issue that must be addressed before the end of the century. According to climate statistics from NASA, the planet’s surface temperature has risen by over one degree Celsius since the 1900s, Arctic sea ice coverage has decreased by over 13 percent, and carbon dioxide levels are at an all-time high. Though these statistics might seem negligible, the repercussions are massive: the entire globe is experiencing more extreme weather events, loss of agricultural produce, and the extinction of certain important species. Scientists are constantly researching solutions to combat these pressing issues. In a recent study, scientists discuss the possibility of employing the aid of another species of organism: bacteria.

Through millennia of evolution, the abundance of microorganisms and their many unique cellular pathways make them particularly interesting to scientists studying climate change. For example, marine phytoplankton are capable of performing more than 50 percent of the planet’s carbon fixation, while diatoms are responsible for storing over 40 percent of carbon in the ocean floor. A study from the Vienna University of Technology examined a special family of bacteria called acetogens, which are able to metabolize formate to create formic acid. Specifically, the scientist examined the model organism, Acetobacterium woodii, and found that not only are they very efficient at utilizing carbon dioxide, but it is also possible for them to reincorporate byproducts like carbon dioxide and monoxide into their pathway to generate formic acid, effectively creating a cycle.

In addition, scientists at Vienna University discussed the possibility of manipulating certain genes in A. woodi to create products other than formic acid, like ethanol or lactic acid. These two molecules are very important as organic renewable resources since ethanol can be used as a biofuel replacement for gasoline, while lactic acid can be utilized to make the biodegradable plastic PLA. Furthermore, a study from 2016 discusses the use of certain lactic acid bacteria and yeast species in ethanol production. The scientists from the study hope to mass-produce the 10 identified species of bacteria on a commercial scale, creating enough ethanol to completely replace typical gasoline and power entire cities.

Scientists are also examining photoferrotrophs, special aquatic bacteria known for taking energy from the iron-rich environment they inhabit and “consuming” electricity. Photoferrotrophs use soluble iron as an electron donor and light energy to perform photosynthesis. Their photosynthetic pathway has the ability to efficiently sequester carbon dioxide, prompting scientists to examine whether or not they could be used to combat climate change. In theory, photoferrotrophs would be a wonderful asset to humanity’s arsenal against global warming, but results remain mixed. Scientists, however, are hopeful, especially given how common these bacteria are and the possible impact they could have on the planet.

In a 2020 study published by Natural Climate Change, scientists discovered a class of methanotrophs, or methane-oxidizing bacteria. These bacteria are unique in their ability to sequester methane, a common greenhouse gas that contributes more to climate change than carbon dioxide due to its special heat-retaining properties. These bacteria play a major role in the natural capture and oxidation of methane, especially in wetland and peatland biomes where an estimated 40 to 60 percent of methane is absorbed before escaping into the atmosphere. A decrease in net methane emissions would be incredibly helpful, especially in the Arctic where melting glacial ice is releasing unprecedented levels of methane gas.

In contrast to all the possible solutions bacteria may bring to climate change, a study from Imperial College in 2019 posits the theory that bacteria can drive climate change. Bacteria are one of the most affected species by surface temperature changes, even if it's only one degree. The slight change causes a snowball effect of rapid evolution and special adaptations. As bacteria adapt to the warmer environment, respiration rates and cellular processes speed up, which induces the release of more carbon dioxide into the atmosphere. An experiment with 482 prokaryotes showed that a slight rise in temperature caused an unexpectedly significant rise in carbon dioxide respiration. The theory is still under testing, and the scientists in the study simply want to caution that “it's important for climate models to take into account [prokaryotes’] higher sensitivity to temperature change at both short and long timescales.”

As the efficacy and use of microbiology continue to expand in the direction of combating climate change, research will reveal the feasibility of such a promising solution. Though there has been pushback against the use of bacteria, the overall notion is in favor of the use of bacteria on a commercial scale to address climate change. The commonality, abundance, and processes of certain bacteria have the potential to create a permanent solution for the issue, but this solution comes with time, appropriate testing, and safety regulations. In the immediate future, humans are the only ones capable of making the change to slow climate change. Through laws, technology, and even daily habits, we should be the ones to mend our planet first before handing the baton to bacteria.