On the relationship between bacteria that break down toxic substances and success in exams
It was towards the second hour of the final exam in the college course, when I received clear signals from the invigilator that one of the students was trying to copy from his friends. Indeed, I clearly noticed a student sending needy looks to the sides, and even leaning forward and not even trying to hide his distress. At this point I decided to intervene. The young potential criminal was immediately removed from the exam classroom for a personal reprimand. The overseer accompanied us, imbued with the spirit of battle and courage.
"What did you think, that you would escape punishment?!" rage
I signaled her to stop. "Please listen," I tried to please his heart with smooth words. "Even if it's hard for you, you can't copy from authors."
It was not apparent that he was excited. "I did not copy." said confidently. "I know the answers to all the questions."
"Have you finished the test yet?" I asked. He nodded his head.
"really." I made it difficult. "So what was the last question?"
"It was a question about the history of evolution," he smiled. "I remember this topic from the lecture. Almost a hundred years ago, people started using a substance called pentachlorophenol to preserve trees and telephone poles. It was a synthetic material that did not exist until then, and bacteria and fungi did not know how to deal with it. He destroyed them easily and efficiently."
"And what happened then?" asked the overseer coldly.
"Because the substance was so new in nature, the bacteria were not prepared for it, and were not yet armed with ways to break it down," he immediately answered. "And it accumulated in the ground and remained for decades. It was also toxic to humans, so they started looking for bacteria that could still break it down, and in the 80s they also found such bacteria: Sphingobium chloropheniculum."
The supervisor raised an eyebrow in my direction. I nodded. Really nice that he remembered the name. "And how did they manage to acquire this new ability?" I spurred him on.
"That's the nice part," he grinned. "They got help from their friends. After all, you taught us in class that bacteria can exchange genes with each other. Some of them collect genes from their dead friends. Others connect to each other by means of thin appendages, thus passing genes between them while alive. And in some rare cases, viruses can even attack one bacterium, kill it and rob it of segments of genetic material and transfer them to another bacterium. There are many ways!”
The caretaker shifted her weight from leg to leg. "He is right?" The theft in my direction.
I nodded my head, wrapped in shingles.
"Absolutely right," I said. "Bacteria really can transfer genes to each other, and a new study published this year showed that Sphingobium was able to get help from two other bacteria, although we still don't know exactly how. The genes from the other two bacteria were integrated into the genetic code of the sphingobium, giving it the basic ability, which was improved during decades of rapid evolution, to break down the toxic molecules of pentachlorophenol."
"Yes," the student yawned demonstratively, "I read this study. Everyone is enthusiastic about the rapid evolution of the sphingobium, but the researchers who analyzed its genetic code in depth admit that the genes it acquired are barely enough to break down the problematic molecules. They underwent a partial evolution that suited them for the role, but they failed to become truly efficient at it. That's why the bacterium is still not completely effective in breaking down the substance. And yet, kudos to evolution.”
"You know quite a lot, for someone caught contemplating copying," I said.
"I didn't try to copy," the student shrugged. "I told you, I knew the material. You are wasting your time. I did not copy. Everyone there is my friend. I'm just trying to help them."
I felt my brow furrow. I couldn't help but think of the sphingobium. He also received help from his friends, in a strange way. In the selfish world of the predatory and preyed bacteria, and out of a constant struggle for existence and efficiency, interactions between the bacteria created a first offspring that was able to deal with the harsh environmental conditions, and perhaps also benefited the other bacteria by neutralizing the toxic substance and removing it from the soil. Just like…
"Madam invigilator," I spoke slowly, "if I am here outside the classroom, and you are outside the classroom, who is supervising the examinees right now?"
The overseer opened her mouth, without a sound.
The student just smiled.
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About the author
Roi Cezana is a researcher in the technological and social forecasting unit at Tel Aviv University, a PhD in nanotechnology from the Technion, a writer on popular science topics and the owner of the blog "Other Science". His book "The Guide to the Future" is about to be self-published and financed through Headstart.
