Diary Page One#
Okay, I know you are very curious about who I am.
I am a descendant of the DH5α strain under the genus E. coli, which is roughly equivalent to a family with a special mission among you humans. That's right, I am not human; I am a tiny bacterium that you humans can only see through a microscope: look at the smallest millimeter scale on your ruler, I am nearly a thousand times longer than that! But I don't think I'm just an ordinary bacterium—I'm talking about in terms of thought, even though our family has indeed played an important role in your biological development—so I decided to document my life and introduce you to the world from the perspective of microorganisms.
I am an E. coli, and it's inconvenient to disclose my height and weight, but no one has specifically measured me, and I don't have much of an idea. According to your human experts, my kind is generally a few micrometers long. Micrometers, you know? That's one-thousandth of a millimeter. Within our vast group of E. coli, there are various strains, such as the BL21 family, which is closely related to us and is often used to express fluorescent proteins. Their special ability is to easily emit fluorescence when they have the fluorescent protein gene inside; while our family's special ability is to quickly replicate something called a plasmid inside. We have a love-hate relationship with plasmids: on one hand, when we have plasmids, we can gain superpowers to resist many harmful substances (like the antibiotics you take to treat bacterial diseases, which we absolutely despise), but the process of plasmids entering our bodies is quite painful for us. It is said that many of my ancestors died in laboratories because of this... sigh, let's not talk about that; there are also many strains like O157 that can make you sick with diarrhea. In short, we are everywhere, so you better wash your hands diligently to avoid accidentally ingesting our pathogenic relatives.
Speaking of my family, sigh, from the moment I opened my eyes, I knew I would probably be a poor child without a father. I was cloned from my mother, who was cloned from her mother (my grandmother), so apart from age, we are all exactly the same, except for my great-great-great-grandmother—she is said to have mutated and was kept by humans as a rare treasure because she had unique characteristics. And because our matriarchal society reproduces through cloning, I have no father. But I accepted this gladly; after all, I don't need a father to teach me how to live. Our pursuit is very simple: to keep producing offspring until we are too old or the environment is unsuitable for survival, at which point we stop asexual reproduction to prevent our group from going extinct. I initially accepted this setup, but over time I found it very boring. The most common topic of discussion among my family members is how to produce a child as perfect as themselves and how to maintain their replicative enzymes (without replicative enzymes, our genetic material DNA cannot double, which would prevent us from having offspring). Because I am a unique and thoughtful bacterium, I plan to travel and see this vast world.
Below is my travel diary.
Part One: The Food Snatch#
As a heterotrophic bacterium, my mother, sister, grandmother, and great-grandmother all expressed strong opposition. After all, we cannot produce nutrients through photosynthesis like the blue bacteria of the green oxygen country, and the food we can store is so limited. I understand their concern for me, but I still desperately want to go out and see the world.
So, I shook my head resolutely, waved my flagella, and gradually drifted away...
Life on the road is full of challenges. For example, today, another vagabond and I both set our sights on a small piece of glucose by the roadside. She claimed she saw it first, but I didn't want to give up the food I had finally found.
"You are..." she mocked, "from the DH5α family?"
"How do you know?" I shot her a glance; right now, I didn't care about anything other than food.
She suddenly leaned closer and said, "I've seen your family of bacteria, you know? Haha, all your family members are disabled! No matter where the plasmids come from, you accept them. How pathetic."
"Shut up!" Although I admit our family has such characteristics, I don't think we are that pathetic. "We are sacrificing ourselves for the cause of science! We are helping humans produce and select the plasmids they create. What about you? What strain are you from?"
"Hehe, not very old, but with quite a temper." She laughed disdainfully, "What do you care who I am? Anyway, I'm claiming this piece of glucose!" With that, she waved her flagella and quickly ran towards the piece of food emitting an enticing aroma.
I gritted my teeth and charged after her: "Why should I give it to you?" But it was too late; she had already picked up the prey and was admiring it closely. Hmph, if I can't provoke her, can I not avoid her? I turned to leave, but the bacterium that snatched my lunch said leisurely, "Tch~ I didn't say you couldn't eat. Since we are both from the E. coli genus, I'll share a portion with you." Although the capable do not accept food thrown at them, in the midst of wandering, life is still the priority. I quickly grabbed this hard-earned piece of sugar and ate it, but found it hard to swallow; it wasn't the taste of home... I suddenly began to miss the warm home: it was always warm and humid, with endless glucose and beef extract peptone, and caring aunties. But I had already forgotten the way home... Tears immediately welled up in my eyes; it was the first time I cried so heartlessly and without restraint after leaving home for so long.
"What's wrong, crying so hard? Don't tell me your PTS system is malfunctioning." Seeing me so sad, the rude vagabond was actually startled by me. "I don't know... Wuwu, I don't know, wuwuwu, I just... miss home... maybe it's wuwuwu, I feel so... so uncomfortable... uwahwawuwu." I was already incoherent.
"Really." The vagabond seemed speechless and just waited for me to finish crying. "Hurry up and eat, or I'll eat it for you." I quickly activated my PTS transport system and absorbed the glucose into my body. "Really, you look like a kid who just ran away from home, so immature." The vagabond scoffed, "Kid, how about you follow me to explore the world? Seeing you so pitiful, I can still treat you to a meal later." She suddenly said with a hint of sadness, "No wonder, why leave home to cause a ruckus? Now it's good; if you want to survive, you have to fend for yourself."
Actually, I didn't like her much, but as a lonely bacterium, it was better to find a companion. So I reluctantly agreed. "Hey, what's your name? You can't not tell me your name, right?" I asked.
"Then, you can call me Sister Bo from now on."
Part Two: I Got Infected!#
Thus, I began my wandering life following Sister Bo.
Actually, Sister Bo isn't a bad person; she just has a sharp tongue. Having survived alone in society for so long, she knows things that I can't even reach, so I often ask her silly questions.
"Sister Bo, what exactly is our PTS system?" Actually, I only knew that we have such a system in our bodies; at home, everyone says, "Quickly activate your PTS system to absorb today's nutrients!" So I vaguely understood that this is probably our system for absorbing food. But, hey, don't laugh at me, do you know what your digestive system consists of and how it works? So, study biology well, young one.
Sister Bo smiled, "Hey, it's rare to see you ask such a high-level question." She pointed to my mouth, "See that hole there? Hahaha, don't think we just put food in there and ignore it; actually, there's a lot of knowledge inside."
"PTS stands for glucose transport system, which is an enzyme system specifically for transporting glucose into your body. Enzymes are made of proteins, and these proteins can act like catalysts to help you quickly swallow glucose. Moreover, there's a strange thing: we eat glucose, but when it's transported into the body, it adds a phosphate group, becoming glucose phosphate. However, I don't quite understand the mystery behind this; humans seem to care about it a lot. Generally, high school students learn about how substances cross cell membranes, including three methods: passive diffusion, facilitated diffusion, and active transport. However, the transport method of our PTS system is not included in any of these three, so if they study biology in college, they will learn about this transport method called 'group translocation,' but they don't really understand it either."
"Um... it feels complicated." I pondered for a moment, feeling that not understanding this advanced knowledge wasn't a problem, so I didn't dwell on it.
During the days of wandering with her, we often bickered about food. Indeed, she could use her experience to know where food might exist; as long as it was near starch or cellulose, she would take me around, rather than just running to places with lots of bacteria to fight for food like I did. However, during this time, we also passed through some very suitable living places, but Sister Bo always said, "I don't want to stay in a greenhouse and lose my freedom, becoming a sacrifice under human control." And I, influenced by her, also didn't want to return to such a domesticated place. I left home precisely because I longed to explore the world, right? So usually, we would have a baby there and then leave, ensuring my child could live comfortably, and I wouldn't feel guilty towards her.
On the journey, I gradually discovered that Sister Bo really knew a lot, perhaps even too much for a bacterium. However, Sister Bo always kept her origins a mystery, and I didn't dare to ask further.
Speaking of which, yesterday, after asking Sister Bo about the PTS system, we continued on our way, searching for food and resting places. Passing by a "refugee area" (actually a culture medium discarded by you humans), Sister Bo suddenly frowned, "Not good, this place is not suitable for long stays." "Why? It looks no different from the refugee areas we usually see." "No, take a closer look; their bodies are more swollen than ordinary bacteria." When Sister Bo said this, I realized it was true: those lazy bacteria leaning against the roadside or lying in the corners indeed seemed to have something inside them. Just as I was about to approach and ask them, Sister Bo suddenly yanked me back. Just as I was wondering why Sister Bo was so agitated, the bacterium lying on the street suddenly exploded! I saw it burst open, and then many holes appeared, releasing numerous small black things from inside. Even though Sister Bo and I reacted quickly, we still inevitably got splattered with some.
It was the first time I had seen such a thing; I was almost going into shock. I hurriedly looked at Sister Bo, who was frantically shaking off the black spots on her body while shouting, "Get up and shake off those black spots! This is a bacteriophage! Oh my god! Shake them off, don't let them enter your body!" But I was already too weak; when I looked down at my body, I found that the black spots were indeed slowly seeping into me. Everything went dark before my eyes, and I fainted.
The last voice I heard before losing consciousness was Sister Bo's frantic shout: "Is there a doctor? Hurry up! She has been infected!"
Part Three: Awakening#
When I woke up again, it was already a new day. However, our sense of time is not the same as yours; after all, in your eyes, we reproduce every 20 minutes, but we feel that this time is very long, equivalent to about half a year for us. The diary entry from yesterday was actually written today because I had been unconscious for a day.
When I woke up, I was lying in a strange place, surrounded by many other bacteria lying on the ground, their bodies very emaciated but their bellies swollen. I suddenly remembered Sister Bo's last sentence: "She has been infected!" So, am I going to die like them now?! "Sister Bo! Sister Bo!" I shouted, and all I wanted to know was whether I was really going to die. What if I wasn't infected? What if Sister Bo's judgment was wrong? What if, what if... she abandoned me? I smiled bitterly; yes, I am an infected one now, and she has no obligation to take care of a bacterium she has no ties to. If she continues to stay in this place, she might get infected herself. Thinking this way, I calmed down instead.
Today, due to feeling unwell, I can't continue writing. Readers, please bless me; I don't want my life to end like this!
Part Four: The Old Hospital#
Waking up groggily again, I vaguely saw a piece of lactose placed beside me. No wonder, if there is glucose, who would eat lactose? After all, utilizing lactose requires us to activate a new gene to absorb and digest it. However, in such a crowded and messy place, having something to eat is already quite good, so I had to endure the poor taste of lactose and absorb it. After temporarily filling my stomach, I forced myself to muster the strength within and walked around to see what it was like. How to describe it? Everywhere were sick bacteria with big bellies, but I didn't see any relatives or nurses. Unlike your human world, only a few healthy bacteria were quickly distributing food, their impatience and fear evident on their faces. On the walls were old reports like "Eight Regulations on the Prevention and Treatment of Bacteriophages Issued by the Central Government" and "Our Hospital's Director Developed a Vaccine Against Certain Bacteriophages." It turned out this was an abandoned hospital. It seems that before being discarded by humans, a very healthy bacterial community system existed here, but after losing the nutrient supply from humans and facing a sudden wave of bacteriophage infections, this beautiful proletarian society collapsed, and the previous welfare was lost due to the lack of supplies, leaving the bacteria poor and miserable.
I thought to myself that my life might end here. What terrified me was that this hospital was filled with a suffocating atmosphere of death; no bacteria attempted to treat the patients, no bacteria cared about the emotions of the infected. We were like the social remnants abandoned by normal and healthy bacteria, waiting to die here. "Puff," a muffled sound behind me made me involuntarily turn around, but I quickly regretted this action: a soft bacterium, terrified, discovered many holes appearing on its body. Before it could scream, it shattered, and black things splattered out from its body, just like what I had seen before. I screamed and desperately ran forward, but in my fright, I found that the bacteria closer to her remained motionless, their eyes revealing despair and helplessness. They had become numb to this death! Other bacteria around even scoffed at my evasive behavior; one patient mockingly said in a "been there, done that" tone, "You’ve already been infected; what are you afraid of? It’s just a matter of dying sooner or later!"
"No! I am not like you!" I shouted angrily, "If you want to die, go ahead, but I will never wait to die here! I must, I must find a way to save myself! Um... um!" Suddenly, my mouth was covered, and I turned around to slap someone. Can't a bacterium live and still speak? However, the person behind easily dodged my strike; only my palm wind knocked off her mask, revealing the entire face of the bacterium: that cynical gaze could only belong to Sister Bo!
Part Five: Escape from the Old Hospital#
"Shh," Sister Bo signaled me with her eyes. Having been with her for so long, how could I not understand her meaning? So I deliberately shouted, "What is this place? Huh? Just bullying us sick patients? Come on, explain yourself!" "You are disturbing the order here and bothering other patients; what do you mean by that? Let's settle this privately, come on!" Half-pushing and half-pulling, Sister Bo and I quickly left the center of the patients and found a quiet place.
"Sister Bo, you..." "I came in to find you!" Sister Bo casually tossed aside her nurse's hat. "They wouldn't let bacteria just enter this place. Don't blame me for not coming to find you earlier; their selection of nurses is quite strict!" After talking with Sister Bo for a long time, I finally learned what had happened in the past few days. It turned out that after I fainted, Sister Bo hurriedly found a few bacteria that looked relatively healthy and asked them where there was a hospital. However, they all hurriedly ran away, afraid of being infected by me. With no other choice, Sister Bo had to seek help from the security room. Who would have thought that the bacteria in the security room were all false justices? They ignored the many infected bacteria on the street, and they regarded Sister Bo as a "reporter" who reported the existence of infected individuals. So, in front of Sister Bo, they swore, "Don't worry; we will strictly control her." Then, this group of government bacteria that only did superficial work threw me into this place. Sister Bo only realized something was wrong after a while and disguised herself as a nurse to find an opportunity to approach me.
"Ah, no wonder this place is so decayed. Even if it hadn't been abandoned by humans, if the bacteria became this corrupt, the world would eventually perish." I couldn't help but sigh. "So the urgent task is to get you out of this corrupt tribe; we need to find a way to escape this old hospital." Sister Bo said decisively, "Otherwise, if you don't get timely treatment, I might get infected too, and we would both die." So, after a bit of scheming between the two of us, we planned to disguise ourselves as nurses and sneak out through the back door. Sister Bo quickly stole a few pieces of nurse equipment and brought a large piece of lactose for me, "Pretend you are distributing food, and later bribe the security lady." Although it felt a bit unethical, we had to lower our moral standards to survive. Sister Bo, having been in society for a long time, led us to quietly slip out through the back door. The security lady was quite happy and said, "Oh, two little girls getting off work so early? Thank you!" Once we left the security area, we immediately started running. The infected bacteria we passed by on the street corners, bridges, and rivers deeply imprinted in our memories—was this what a collapsed society looked like? If the bacteria here could be more united, cooperative, and fair, perhaps it wouldn't be in such a situation.
Suddenly, everything went dark before my eyes: perhaps the bacteriophages in my body were trying to invade my DNA again. I thought I was going to die, but Sister Bo shook me desperately: "No, you can't fall asleep! We have to escape this place!" While she desperately pulled me, she tried to take out food from her body, but we had already run out of supplies. Sister Bo gritted her teeth, "Get on my back!" I felt like I couldn't muster any strength, like a lump of mud stuck to Sister Bo. In a daze, I didn't know how long it had been when I felt something tearing inside my body. I screamed and lost consciousness.
Extra Chapter 1: Thoughts on the Journey: About Opportunities#
Just like you humans, we also have an end to our lives, and one important reason for our aging and death is that our metabolism goes wrong: it may be due to natural slowing down, or it could be external damage from ultraviolet rays, bacteriophages (which are viruses that can infect us bacteria), etc., causing us to become sick and die. Moreover, we are much more fragile than you; even a little harm is enough to wipe us out. If you humans get a benign tumor, it can still be treated; after all, that's just a part of the DNA of a few trillion cells in your body that has errors. You just need to surgically remove the faulty part. We can't do that; we are a single cell, so if something goes wrong with our DNA, it's basically game over for us. Therefore, mutations (sudden changes in DNA) are undoubtedly a death sentence for us, except for my great-great-great-grandmother—she mutated and turned misfortune into fortune, not only surviving but also being revered for gaining a unique ability. Now her descendants are spread across major microbiology laboratories.
Let me tell you about the glory of my great-great-great-grandmother.
It is said that at that time, our ancestors were still living in human laboratories, and scientists would check on our reproduction status every day. Sometimes we would see scientists deliberately applying some survival pressures like low temperatures, ultraviolet rays, and sugar deprivation to the bacteria they raised, allowing the fittest to survive—selecting individuals that could resist this pressure while those that couldn't would leave this world helplessly. Sister Bo was right; we laboratory bacteria have always lived at the mercy of humans; the useless ones are ruthlessly eliminated. Our family survived because we proved our value early on (amplifying plasmids), which was fortunate. When my great-great-great-grandmother was just born, she looked the same as the other DH5α bacteria in the family, but after a while, one summer, she and some bacteria from the family were taken out of the culture medium by a graduate student. When transferred to solid culture medium, they were mistakenly placed on a windowsill. Although the graduate student quickly realized and put the petri dish back into the 37-degree incubator, the nearly 50°C high temperature baked most of the bacteria to death. A day later, the graduate student was pleasantly surprised to find that my great-great-great-grandmother not only survived but also gave birth to many bacterial babies. Later analysis revealed that this was due to a mutation in her DNA, which allowed her to produce a protein that other bacteria did not have. This protein was very optimistic and proactive, so even the proteins that were negatively affected by the high temperature could be mobilized by it, allowing my great-great-great-grandmother's body to withstand high temperatures without collapsing. Later, this gene attracted a lot of attention, and my great-great-great-grandmother even made it to the cover of a magazine!
However, my great-great-great-grandmother was a lucky one, placed in harsh conditions where she could survive. Many bacteria, due to being placed in the wrong conditions, not only did not have glorious lives but also lost their lives: for example, my aunt, who used to eat with me often, proudly showed me her mutation that allowed her to produce a protective protein against penicillin. However, she was later placed in a culture medium with erythromycin and ultimately died at the hands of erythromycin. Her last words were, "I don't blame myself for not having the ability to resist erythromycin; I only blame that graduate student for not placing me in the right position." It seems that you humans often have similar situations in life, like a talent scout recognizing a fast horse—liberating a capable horse from carrying goods and letting it achieve great feats on the battlefield. So, having a discerning talent scout really is a fortunate thing. However, you humans are happier than us because you can choose your careers and majors based on your interests and talents, unlike us, whose fates are dictated by researchers. So you must use this advantage to live in the right position and lead a happy life!
Extra Chapter 2: Things Learned at Home: About DNA Replication and Having Babies (1)#
Speaking of which, bacteria are destined to die, so what we care about most is the social value we create—the ability to produce offspring through asexual reproduction. When having babies, what we bacteria need most is to pass on the DNA that sustains our survival to our offspring. If we encounter problems while replicating DNA, it's like when you copy homework problems; if the copier malfunctions and prints "1+7" as "1-7," your answers will certainly differ from the standard answer. Moreover, if you continue to use a good copier to copy this "1-7," it won't come out as "1+7" either. This error will make her children and their children suffer greatly. Therefore, we pursue completeness and correctness when replicating DNA.
DNA is our genetic material, and it is the genetic material of everything from viruses to your advanced life forms' cells. It can control a series of physiological activities. For example, when the temperature is extremely high, my great-great-great-grandmother can produce a protein that adapts to high temperatures, and this protein is produced through a series of manufacturing processes from DNA. With the help and encouragement of this protein, other parts of her body can also be mobilized by this protein, allowing her body to carry out metabolism under high temperatures. However, most E. coli do not have DNA that can produce such positive proteins, so they feel, "Ah, why is it so hot? I don't want to live," and thus give up having babies, leading to their demise. In short, DNA is equivalent to the core of our lives; without DNA, no living organism except prions can survive.
Speaking of prions, they are a freak; they cause chaos everywhere, and mad cow disease is caused by them. This freak has no DNA, only proteins, yet it can replicate. Its method of replication is to incite originally diligent proteins to jump ship and join its cult, ultimately becoming the reactionary proteins assimilated by it. The seduced reactionaries will then pull their colleagues and classmates into the cult, leading to a rebellion of proteins in the animal's brain! Then the animal will suffer from mental illness and die pitifully. No wonder in our world, it is often referred to as a terrorist that "made a deal with the devil." So, you humans must never join a cult; otherwise, your world and your beautiful society might be destroyed by yourselves!
Sigh, every time I talk about this freak, I get angry; it has harmed too many lives! Forget it, forget it, let's not talk about it. Oh, one last thing: the best way to prevent this freak from entering your body is to make sure to cook beef and lamb thoroughly. Even the most high-end steak in a restaurant should be well done, as this devil's heat resistance is simply intolerable.
Okay, let's stop here. In short, DNA is the most important part of our bodies, and to ensure that our offspring can live well, we must guarantee that every replication during reproduction is flawless. Therefore, its health has always been a hot topic among women of all races. Bacteria do not need to find boyfriends or girlfriends, so we are usually carefree, but when it comes to DNA replication, we never dare to be careless because the most important thing in our lives is children. If our bodies are not healthy and we give birth to disabled children, we will be laughed at—although we only care about giving birth and not raising them. Bacteria have an instinctive understanding of how to absorb nutrients and reproduce. We place great importance on our DNA replication system, just like young girls among you humans always think about how to take care of their faces. We also think about how to maintain our replication system so that we can keep reproducing until old age. Generally, our DNA is replicated first, split into two parts, and then we stretch our bodies as much as possible. When we break apart, our bodies can quickly flow like the surface of a soap bubble to fill the gap, so they won't break.
Extra Chapter 3: Things Learned at Home: About DNA Replication and Having Babies (2)#
Now the question arises: we are very cautious about DNA, and it takes 40 minutes to replicate once, which is about the length of your class. However, our bodies are filled with the desire to reproduce and split every 20 minutes. What to do? Haha, actually, we are quite clever: we increase the number of DNA replication systems! DNA is long, and for those small DNA polymerases, it is like a long single-sided zipper. They and their buddies run along it while building a new side that can fit perfectly with the original single-sided zipper. After a group of polymerases runs far away while replicating, we will place two more batches of polymerases at the two starting points to let them run and repair the DNA zipper. Then, when the first batch of polymerases completes this "zipper repair marathon," my body starts to split, and then one of the batches that made the zipper will follow into my daughter's body. My daughter can produce new polymerases through inherited DNA and quickly start a new round of replication marathon.
This way, we can ensure that even with a replication speed of 40 minutes, we can complete the task of splitting every 20 minutes. The repaired zippers will temporarily come together, and when the next replication is needed, the zippers will be opened by helicases, and the two single strands will be replicated separately, with one remaining in the mother and the other passed to the daughter.
However, there is another very important question: what if our DNA is accidentally damaged? Our ancestors have suffered this pain, so many ancestors without self-correction mechanisms for DNA unfortunately went extinct, and those alive today are descendants of bacteria with self-repair mechanisms. This confirms Darwin's saying, "Survival of the fittest."
Our DNA has four self-repair mechanisms. The first one has a very pleasant name called "photoreactivation," which can directly repair the abnormal structures formed by ultraviolet light on DNA under natural light. However, only we bacteria can do this; you humans cannot repair DNA by sunbathing. However, it is good for your children and the elderly to get some sun, as it can synthesize vitamin D to help your bodies absorb calcium. The second one is named "excision repair" by you humans, and the third is called "recombinational repair." Um, since I, as a bacterium, didn't understand the complex principles explained by Sister Bo, I can only barely distinguish that excision repair involves cutting out the incorrect part and then re-completing it, while recombinational repair involves cutting out the entire segment with the error and then repairing that segment of DNA. The last one is interesting; it's called SOS repair. After an error occurs, our enzymes become flustered, and to complete the workload, they randomly find a part to patch up and continue working. As a result, the places that should fit correctly bulge out or sink in, forming a strange pairing. The offspring's DNA may mutate, and the newly born bacteria might be disabled or even die because other enzymes related to DNA cannot run on it. However, a few bacteria may turn misfortune into fortune, but the probability is really small. Therefore, we don't seek to have abilities beyond ordinary bacteria; we just want to be a good ordinary bacterium! This is also why we are so cautious about DNA replication.