Have you ever thought about the ability of being born with knowledge? It sounds like a plot out of a science fiction novel, yet recent research discovered that Escherichia coli (E. coli) bacteria, despite not having a brain, are able to remember past encounters with nutrients and pass this information down to their future offspring. This discovery not only surprises microbial behavior scientists but also reveals the challenge behind the fight against antibiotic resistance.
Swarming of Bacteria
George O’Toole, a microbiologist at Dartmouth College, explains that while “we typically think of microbes as single-celled organisms,” they actually operate in collective units or swarms. Interestingly, when they move in swarms, they become stronger against Antibiotics because there are more of them close together. According to this article from Missouri Department of Health and Senior Services that explain what is Antibiotic resistance, the reason E. coli bacteria become stronger against antibiotics when they are close together in swarms is due to their biological mutations, DNA exchange, and rapid reproductions. Mutations are essential to evolution, they can bring genetic variation (good or bad) to a specie. Because of the vast number of bacteria present and their high reproduction rate, many mutations can occur in a swarm of bacteria. Through random mutations and selection, bacteria can develop defense mechanisms against antibiotics. After some bacteria have developed some anti-antibiotic genes, bacteria will actively swap bits of DNA among both related or unrelated species. Thus, antibiotic-resistant genes will spread rapidly among a swarm of bacteria and can can even be incorporated into other species of bacteria. Finally, given the fast reproduction speed of bacteria, it does not take long for the antibiotic-resistant bacteria to fill up a huge portion of the bacteria population, therefore disabling/nerfing the effects antibiotic drugs.
Collective Memory of E. coli
A team of scientists, as reported in the Proceedings of the National Academy of Sciences USA, found that E. coli bacteria swarms have a form of memory that correspond to their exposure to nutrients. This experiment, led by Souvik Bhattacharyya from the University of Texas at Austin, observed unusual patterns in E. coli colonies. Through deeper examination with his science team, they concluded that these bacteria acted differently because of their previous experiences. Specifically, bacteria from colonies that had swarmed before were more likely to swarm again. This behavior was passed down to their descendants for four generations, suggesting a genetic memory of past actions in the bacteria.
By Cancer Research UK – Original email from CRUK, CC BY-SA 4.0, Link
Genes that are Responsible for this Behavior:
Further investigation was conducted to this phenomenon concluded that two genes responsible for iron uptake and regulation is the keys to bacteria’s memory. Bacteria with lower levels of iron, an essential nutrient for them, are more likely to move collectively(in swarms) to find environments with higher level of iron concentration. In addition to the past research that shown that many bacteria can remember and pass to their offspring of the description of their physical surroundings, this study suggests that bacterial can also remember and pass to their offspring about nutrients’ presence. This ability of bacteria to remember and pass on knowledge about physical surroundings and nutrient existence demonstrates bacteria’s evolution journey.
Purpose?
This research increases our understanding of microbial life, showing that bacteria like E. coli can remember more the physical environments and can also recall the presence of nutrients. These memories will affect their decisions on where to settle and can increase their chances of surviving and fitness. O’Toole believes that this mechanism of bacterial memory is probably not exclusive to E. coli; it can actually be a common mechanism that exists among many different types of bacteria. The insights gained from studying these E. coli at a molecular level can provide valuable context for the development of antibiotics, offering new approaches as traditional antibiotics will eventually lose their effectiveness.
Connection to AP Bio
In AP Biology, we’ve learned about Cell Signaling molecules and mechanisms used by organisms. Bacteria can also communicate amongst them when they are close together through a process called Quorum Sensing. Bacteria will secrete small chemical signaling molecules which will be detected by other bacteria nearby using their receptors. Through Quorum Sensing, bacteria are able communicate with others of their kind, sharing information about bacteria density and adjust gene expression accordingly. In addition, we will also be covering information about DNA, Heredity, and Evolution during this year in AP biology, which are also significant themes in this post. Numerous mutations will occur in swarms of bacteria due to their large number, this mutation of their DNA can occasionally cause significant change. If this change is extremely positive and can do this bacteria good, through natural selection, this gene will be kept and pass on to future generations of bacteria so that more and more bacteria will have this trait. This is the reason behind my antibiotics are slowly losing their functions. More and more bacteria have mutated and can resist the effects of antibiotic drugs.
What are your thoughts?
A couple of years ago, I often watched cartoons that portrays a type of technology that can give knowledge and pass memory to a newborn baby. I thought that it was a fascinating and unrealistic idea. However, during my research, I surprisingly found out that bacteria seemed to have this ability to pass on their memories to their offspring. What are your views about bacteria’s ability to memorize and pass their memories on to future generations? Do you think this experiment is helpful to future development of antibiotics? Feel free to leave a comment below and we can discuss more about this topic! For more information on this post, go to ScientificAmerican.com for the latest research and updates.
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