How cell cultures made me more hygienic

FOR SURE. It has definitely changed the way my friends, colleagues and I do certain things in our daily lives.

Like how my colleague would spray her phone, wallet and water bottle with 70% ethanol before dumping them in her bag at the end of the work day. 

Or not bringing food into washrooms/toilets.

Down to not getting on the bed in our ‘outside’ clothes.

Now just wait a hot minute.

This ain’t a new concept, isn’t it? 

Its the same idea as to why you’d never dip a spoon with strawberry jam into a jar of peanut butter. Same reason why you should never rub your eyes after touching lift buttons. Same reason why your parents would have slapped something out of your hands as a kid, and exclaim, ‘EH. DOn’T ToUCH. DiRTY.’

The fear of contamination. 

Whilst learning the technical concept of ‘sterile‘ has definitely made me more hyper-aware of the ‘why’s (cue gory yet fascinating pictures of infections caused by microbes), it is definitely something that has been instilled in us as kids.

Our parents and grandparents knew the danger of not being hygienic, having possibly learnt it the hard way, through disease. While most of us have had the privilege of learning ‘why’ through school.

Like yeah, yeah, wash your hands to get rid of germs. But it is only when you see the getting-rid-of-germs part that will really hit home. A lesson that will stick to you for the rest of your days. Funny how that lesson only registered in my noggin’ when I was 18.

Right. Let’s go fellow nerds.

Cell cultures.

Bottles, plates or tubes ranging in different sizes, filled with pink liquid. You’d see them in stock photos.

person doing an experiment
Photo by CDC on

Oh wow, okay, um stock photos have come a long way. This picture above, is accurate (it has to be, its from the CDC wew). But more on that later. 

For now, just look at that picture. 

Now imagine baby microscopic Pokemon are inside the liquid and you have to ensure they are happy and healthy else you ruin your experiments and needtostartalloveragain. AKA another three days…or perhaps if we’re working with really stubborn cells (think a Metapod or Magikarp), then maybe three weeks.

Or a month. 

It is not a rare thing to hear scientists working on these say that they have to drop by the lab on weekends because they need to ‘check on my cells’- 

-as if they’re pets.


They kinda are. 

The media (liquid) that they live in, has to be changed every few days. To reduce the need to come back on the weekends, Fridays are usually busy days for labs that do cell cultures. Imagine having to come back during long holidays. Yikes.

These little microscopic Tamagotchis are super vulnerable to the conditions of the incubator, the concentrations of the ingredients in the media and most importantly, contamination. 

Viral, bacterial and/or fungal.

Well, technically, if contamination happens, there are definitely ways to save the culture. But if it persists after those steps (i.e. increasing the amount of antibiotics), then one would have to restart the cultures. AKA restarting the experiments. And that’s why scientists/research assistants absolutely dread contamination.

How do we spot it then?

First, by colour. The pink colour in the media is a pH indicator known as Phenol Red

In the presence of contaminants, the pH becomes more acidic and will turn yellow. Thus, opening the incubator to see yellow hues would usually prompt a painful groan.

Second sign: cloudy media. Sometimes, the contamination would progress till the entire flask or well would turn cloudy. Leave it long enough and it could turn green. If you’re lucky, fungi will start sprouting.

contamination gif
A 48-well culture plate with saline samples mixed with media. We’re testing for the presence of bacteria, to see which saline sample is contaminated.

Here ya go. Some snippets of real-life contamination. These don’t contain cells but the samples do apparently contain bacteria, which has turned the media green/blue over time. We suspected that it was Pseudomonas, a family of bacteria known for their green colonies on agar plates. Note the wells in the 3rd and 4th row that at first appear clear but is cloudy when checking under the light.

If we look at one of those cloudy samples under the microscope, we’d see tons of wriggling things that look like worms.


Once a culture gets cloudy, *sigh*. In this case of a plate culture, if the samples contained cells, I would have to quickly transfer the unaffected samples to a new, sterile plate. This is because bacteria/fungi/viruses can affect those over time. The conditions in the incubator gives the perfect environment for these critters to jump wells or culture flasks and float around inside the incubator. A menacing threat to everyone. Furthermore, because cells need to breathe, the culture plate/flask/dish is never tightly sealed. This leaves space for enough air (and microbes) to enter. 

Exactly how do these microbes float around to terrorise healthy cells? 

No wings. They just hop into tiny aerosol droplets. Mini, mini water droplets.

Aaaand that’s why you shouldn’t bring exposed food into washrooms. Flushing toilets without the lid produces aerosol droplets of poop and pee. 

Kinda like sneezing without covering your mouth.

Soooo, wear a mask, guys.

Thus, to prevent any pesky bugs from screwing up the culture, we use aseptic techniques.

The main idea of these techniques is to minimize exposure, contact and aerosols. For example, not leaving the incubator door open for too long. This reduces the number of bacteria or fungi in the air entering and potentially multiplying and contaminating everything.

Also, anything that goes into the biosafety cabinets (the metal workbench with a glass pane in front of your face), has to be wiped down with 70% ethanol. Your gloves included. Our hands would be drenched in ethanol, to the point where opening tubes would become laughably difficult.

Context: I can usually open it with one hand. Thoughts: ‘他妈的.’

Minimising contact would mean this: your gloves literally do not touch anywhere else except the pipette and the edge of the culture plate and the outside of lids of tubes/bottles.

And your pipette tip does not touch anything but the liquid it is supposed to take up.

A perfect illustration of that is shown above (that pretty stock photo from CDC). Meaning if you accidentally tapped the pipette tip on a surface before you can reach that 50 mL tube of media, nope. You gotta throw that tip away. 

You can risk it…but is it worth it though?? 

Minimising aerosols means being gentle. No sudden movements = lesser moving air = reduce floaty bugs from entering the cultures. Liquids are pipetted with zero splash. Rule of thumb: the lesser movement, the better. E.g. no passing your arm over an exposed plate.

Not long after my first encounter with these principles, I noticed a newfound awareness when it came to personal hygiene. 

Take, contact lenses for example.

I do not keep my contact lenses and solution in the bathroom because it’s warm, moist and for most of the day, dark. My fingers do not touch the insides of the case unless it is to fish the lenses out. In fact, there are tiny tweezers that you can wash and use for this step now! The contact lens case is also left capped as much as possible. As if the wells are incubators.

…Heck. They kinda are.

In the kitchen, double dipping is a sin. Unless I’m boiling the thing that has been dipped into.

The toothpaste tube doesn’t touch my toothbrush. Only the paste.

Only the paste.

I’m amazed I ain’t a complete germophobe.


In fact, there has been growing awareness of such techniques when it comes to skincare. The spatulas given with tubs of cream? That’s reducing contact.

Not only that, skincare junkies also pay more attention when it comes to packaging: squeezy tubes over tubs of creams, spray nozzles over roller balls for perfume. That right there is reducing exposure. 

The good ol’ don’t bring food into the toilets? Aerosols. I used to think my parents simply said that because it’s considered bad luck or just dirty because we make poops there.

Essentially, if you are one who strategises how to reduce exposure and contact of surfaces in little things like that, now you know the term for it 😉 Good job and keep at it, especially during the current pandemic. And to everyone else, I am positive that you have unknowingly practiced these techniques too. Absolutely positive.

If you can’t think of an instance where you did, try this: minimise exposure, contact and aerosols by staying home, social distancing and wearing a mask.


Welp, I hope I didn’t bore ya. Do let me know what you think of such posts and what you’re curious about today or perhaps a science-y topic or question you’d like me to tackle! 

Till the next one,

Wash your hands.


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