Saturday, February 21, 2009

Picture a Day - Day 80

Hello and welcome to another addition of "Science so easy even a monkey can do it."

Our topic for today involves a few simple solutions, a bacteria plate, and one piece of equipment. It's Growth Curve time!

Okay so last night you should have isolated your bacteria on a plate, and autoclaved your media of choice so nothing else would grow into it. I'll just wait while you get caught up doing just that. No rush really, this experiment only takes 7 hours.

All ready? Good. Now just take out your pipette and divvy out the media into large glass tubes (that were also autoclaved).
Now for colony picking. This is by far the hardest part of the growth curve and you may have to help your monkey out. You want to add just one single colony of bacteria to each tube to control the amount added. So you need a steady hand to pick one small white dot that sits right next to another white dot.
After swirling your loop inside of the tubes to release all the bacteria time to lightly cap them off (you don't want to completely close the lid or no gas can get in and the bacteria die) and put them in the incubator for a few hours.
While those are growing up enjoying that wonderful feast you prepared for them you may want to take this time to catch up your lab notebook, or feed some cells, or if you really feel so inclined to actually get to that evil PCR.

Now that the 2 hours is over, time to pull the tubes out of the incubator and use that one magical piece of equipment.
What it does is measure the optical density of the bacteria cells. As they grow the bacteria become more and more clouded so less light can shine through. It's that absorbance or percent transmited of light that we measure to determine which grows best out of the different media.
After checking every 1 to 2 hours the growth should eventually peter out and you'll have a nice cloudy mixture inside of the tube. Hello, my little bacteria friends. Say hello back!
And that ladies and gentlemen is how to prepare a growth curve. Now I expect you all to start your own little bact labs growing up and ODing bacteria to your hearts content.

2 comments:

Cleric at Large said...

You make me a little homesick. I had a few co-op lab jobs in my undergrad before I completely changed fields.

A little bit of serological identification here, some enumeration (by bioluminescence) there. And of course, as low tech on the totem pole, lots and lots of "other duties as assigned" (hey there, co-op student, I think the autoclave needs cleaning!)

Those were good times.

Chesney said...

I am on my way to start one now - HA! Very interesting, I can tell you love your job!