Chapter 14
Chapter 14
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Translator: penny
Chapter: 14
Chapter Title: Discovery of Bacteria (4)
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Class wasn't over yet.
Estina and the other faculty students were all staring at me. Some looked a bit more tired than when we started, but a few still burned with curiosity or academic fervor.
"Look here. An organ system is made up of organs, and organs are made up of tissues. So, what are tissues made up of?"
Estina blinked her vacant eyes again. Organ systems, organs, tissues... So what?
"Estina, didn't you say you graduated from the faculty? How do you not know this properly? Oliver, answer me."
Biology, and one of its basic principles.
Structure and function are closely linked.
The reason living organisms' basic building block is the cell is because that fundamental unit must be a structure that separates itself from the outside world while sustaining life activities.
"Uh... I don't really know."
"Think logically. Life activities ultimately involve separating and controlling the internal environment from the external one. The basic unit of life has to have a similar structure—a small room-like setup."
That's the cell.
I went back to the human diagram I'd drawn earlier. Individual, organ system, organ, tissue. The final stage was the minimal unit of life activity.
Cell.
Most faces showed confusion, but the cell theory wasn't just proven by observation. It was a fact, and also a logical conclusion that made perfect sense upon reflection.
"That's it for today. If no questions, class dismissed. See you next week."
And with that, the lesson wrapped up.
There were no questions. Some students looked like they had a ton, but going overtime would inconvenience everyone. Plus, crucially, I was exhausted. My mouth hurt from all the explaining.
I might've rushed the end a bit from fatigue midway through, but I'd said everything I wanted to.
As soon as class ended, Estina walked over to me, clutching a stack of papers. Looked like she'd been jotting something down, but I had no idea what.
"I finally get what you meant the other day! Well... proof's still needed. But with the microscope, it'll be quick."
Exactly.
The experiments we'd run for the next little while were straightforward anyway.
Now that we'd figured out how to make culture medium, we'd prepare it, grow bacteria, stain the bacterial colonies, and observe them under the microscope. That should all wrap up today or tomorrow.
"Experiment today too?"
"Yeah. I'll show you how to use the Petri dishes."
"Ah."
Back in the modern world, there were ready-made custom nutrient solutions for whatever bacteria you wanted to culture. Couldn't do that here, which was a shame.
Wonder what would grow in bean-based culture medium. Probably super common ones like Staphylococcus aureus or Streptococcus—yellow grape-like clusters or chains. The specific type didn't matter right now anyway.
The lab.
Estina and I slowly poured the culture solution from a kettle. The starch-mixed bean flour formed a thin film coating the bottom of the Petri dish.
"This should be enough, right?"
The culture medium solidified right on the Petri dish. Like super thin green bean jelly.
I nodded, and Estina put the lids on. It took a few steps, but we ended up with nine prepared dishes.
"What happens now?"
Now we inoculate the Petri dishes with bacteria.
Simple process.
Spread bacteria-containing solution onto the dish using sterilized tools. The microbes settle and form colonies.
Colonies are visible to the naked eye. You can physically isolate specific ones or transfer them for further study. You can even count the number on the plate.
That method indirectly quantifies bacteria in a solution too.
Anyway. I lit an alcohol lamp and sterilized the needle tip in the flame. Just wait a bit for the dish and needle to cool.
Today's test solution? Plain water I'd dipped my hand in and out of.
The needle streaked across the Petri dish.
"When inoculating, make the paths dense but non-overlapping. Overlaps can cause colonies to merge."
"Ah."
"Goal is getting bacteria to form colonies on the dish. Not sure if it'll work great, but something should grow."
Bacteria were everywhere in massive numbers anyway. If not bacteria, fungi would pop up. Estina scratched her head.
"You said bacteria are too small to see. How does growing them change that?"
"In a controlled environment, they form colonies—clumps of bacteria millimeters across. Visible and manipulable."
Once bacteria form colonies on the dish, you can stain them, put them under a microscope, or subculture for research.
"How do you know all this, Professor?"
"Did it before."
I handed the needle to Estina.
"Your turn."
Estina glared at the Petri dish, and I checked the clock. 4 p.m. How long for bacteria to grow?
Staphylococcus aureus colonies take about 12 hours. It was 4 a.m. now, but scholarship knows no day or night.
I shook Estina awake in the library. She'd passed out mid-study.
"Estina. Up."
"P-please... spare me... I was wrong..."
Sleep-talking, huh.
"Time to check the bacteria."
"Don't wanna..."
You chose grad school. Grit your teeth and bear it, Estina.
Estina fiddled with her messy hair, rubbed her eyes, and slowly got up. Only then did she seem to grasp the situation.
"Sorry. Pretend you didn't hear that."
"Okay."
Estina avoided my gaze.
"Bacteria all grown?"
"Should be by now."
"Let's check... But Professor, couldn't we have waited till sunrise?"
We arrived at the lab.
Culture successful. But barely any visible colonies. Fewer than ten per dish maybe. Why? Whatever the reason, Estina was amazed.
"It really worked like you said. From growth to colony size. Just move one under the microscope now."
I nodded.
"Now we just look under the microscope."
"Random question. Do bacterial colonies keep growing if left alone?"
No.
Bacterial colonies lack systems to transport nutrients or oxygen inward. They can't exceed a certain size.
"They hit a critical size and stop. Nutrients don't reach the center."
Estina jotted something in her notebook.
"I'll grab a glass slide."
I carefully picked up one colony with tweezers and placed it on the slide. So far so good. Now, how to fix the bacteria in place.
I dropped distilled water on the colony, then passed the slide over the alcohol lamp to dry.
Sample prep almost done. Just staining left. Estina dripped stain onto the sample.
Oh, right.
Staphylococcus aureus grows best at human body temp—around 36.5°C. Room temp culture meant suboptimal results.
Eh, one colony's plenty.
Now wait a bit.
"Sleepy."
"Nap later."
"What do bacteria look like?"
"Boring. Usually spherical or rod-shaped. Some weird ones occasionally."
Like the spiral Treponema pallidum. But we lacked the tech for that. This microscope was barely bacterial-resolution.
Time to look.
I slid the sample under the microscope. Focused... Huh. Worried for a sec, but clear view. Round purple granules clustered together.
Definitely Staphylococcus aureus.
Makes sense why they're called grape cocci. Bunched like grapes, and Gram staining turns them purple.
I pulled away from the eyepiece.
"Estina. Come look."
Estina peered in.
"They're really there... These are bacteria?"
"Yep."
Estina sat back down, face like a kid who'd just unwrapped birthday gifts.
"This'll open new horizons for humanity. Maybe the century's greatest discovery."
I got the excitement, but too soon to celebrate.
This was just the start. Microscope credited to Hooke, staining to Gram.
Still needed Lister's hygiene realizations in clinical settings, Pasteur's experiments proving germs cause disease.
"Let's write up the results. Need the paper done quick to present sooner."
Estina nodded.
Right, was gonna visit Professor Klaus after class, but missed it.
Still, tangible results should smooth the talk, right?
Organize the experiment details first, then go.