Despite the fact that scientists are discouraged from personifying the organisms they study it’s hard not to do this with bacteria. This is because despite bacteria being single celled organisms they are extremely complex, elegant, and let’s face it, they have a lot of personality. For example, bacteria have various different systems all designed to sabotage other bacterial brethren, one of which is literally a ‘molecular cross bow’. When you hear these things it’s hard not to picture these organisms as micro knights fighting amongst themselves for their land. Another fascinating system bacteria have adapted (and is most likely why they have survived for billions of years) is sporulation.
Bacteria, like humans, experience long periods of starvation occasionally in their lifetimes. People have dealt with famine by adjusting their diets to rely on carbohydrate heavy food (potato famine anyone?) and their bodies increase the use of the glucose that is stored throughout the body. Bacteria have a different approach (and it doesn’t involve potatoes). An environmental stressor (most commonly starvation, but other stressors include: desiccation, extreme heat, etc.) alerts the ‘master regulon’ Spo0A (but his friends call him Reggie). The master regulon has the job of controlling 103 genes all related to sporulation. Imagine a switch board with 103 switches that are all in their default positions that Spo0A begins to switch when it receives the signal to sporulate. When these genes are switched on (or in some cases switched off) many physiological and biochemical changes begin to occur. For example, the DNA in the cell begins to replicate, a membrane begins to start to form around the pile of new DNA, and finally the new DNA gets a protein coat (very stylish) and bursts out of it’s mother cell, thus killing the mother cell in the process.
I know, it’s pretty sad, right? You know what makes it even more devastating (I’m surprised George R.R. Martin didn’t come up with this one) once the cell begins this process, even if suddenly food becomes abundant again, they can’t stop the process. Their sacrifice for their species becomes completely unnecessary sometimes and there is nothing they can do to save themselves. Okay, okay, I’m being dramatic, but it’s pretty darn cool, right?
When I first learned about this process I could help but think about superman’s origin story. Come on, you know it. Let me remind you. Kal-El (superman) is born on the affluent planet of Krypton to his parents Lara and Russell Crowe… ahem… I mean Jor-El. However, the couple’s happiness ceases when they learn of Kryptons imminent demise. Jor-El begins to build a space craft that will successfully allow the infant to leave the planet (because floating around in space and dying slowly is apparently better than a quick death). Krypton explodes, but not before the baby space craft flies into the darkness of space and we all know what happens next.
This is a perfect analogy for sporulation! Jor-El and Lara are facing imminent death (just like a bacterial cell without a food source) and in order to insure the survival of their species (Kryptonians, Bacillus subtilis, same thing really) they put their energy into making a secure, protective casing for their genetic material. These spores can survive for years, in some of the extreme temperatures and environments, some have even been found in fossils. They are almost as tough as Kryptonian metal (which is seriously a thing) and yet they’re not science fiction, they’re just science.