For those of you that haven’t already heard me complain about it a million times, I am presently taking 15 semester hours of science classes. This includes microbiology which I like more than I expected. Others that have taken this class have warned me that this was a super hard class and i was nuts for taking it with other science classes. I dig it. It’s not that hard with effort and I get to grow bacteria outside of my refrigerator – on purpose! (gross AND geeky)
Our Experiment
We were given two unknown types of bacteria to culture and grow. First we looked at the microorganisms under microscopes and inoculated test tubes with them, then transferred them to different culture mediums to try to narrow down exactly which bacteria we were given. I could just spare you the sciencey details about Mannitol and bacillus cerus and blah blah blah and just show you the photos I took in my lab today, but you can read the details if you really wanna. The shots are not that impressive, but I thought it was kinda cool — and how often does a person get to shoot stuff like this??
Bacillus cereus
Bacillus cereus. How is this bacteria relevant? There was recently a recall on products that had been purchased by the hospital due to this bacteria. It was suspected to be on alcohol pads and individual tubes of lubricating jelly. Trust me. You don’t want B. cereus going anywhere that those products are likely to go. The plate is made of starch. B. cereus eats starch. If you drop iodine on the plate, as you see here, it will pool in a halo around the colonies where the bacteria has eaten the starch. Hence this almost pretty Petri dish.
Staphylococcus aureus
This bacterial is growing on a Mannitol salt plate. Mannitol is basically a salt and sugar growing medium. According to Wikipedia Mannitol “was originally isolated from the secretions of the flowering ash, called manna after their resemblance to the Biblical food, and is also referred to as mannite and manna sugar” It starts out a pinkey-red color. Most bacteria will not change the color of the mannitol salt, unless they are halophiles – ie salt/sugar lovers….the more the better. Halophiles will turn this medium yellow. Based on this and the list of possible bacteria we were given, the bacteria growing here is Staphylococcus aureus. Most cases of S. aureus are not pathogenic (disease-causing) but can cause food poisoning and a number of other illnesses.
Last one, ladies and germs.
Escherichia coli (pronounced Esh-er-eekie-uh)
This bacteria is growing on an EMB plate, which basically it two different dyes that have properties that, when inhabited by E. coli, give the bacteria a shiny, metallic-green sheen. In the light, it shimmers if you rock the dish, like a hologram almost. It’s the prettiest pathogen I’ve ever seen. Interesting E. coli fact: Yes, it can make you sick, but it is also used therapeutically to treat people with gastrointestinal troubles.
Well, I’ve watched about all the Bill Nye the Science Guy I can handle for one day and I am so done looking at these photos.
Now go wash your hands!
xoxo
A
