Monday, February 28, 2011

Is there anyone out there?

As it’s been already two lab sessions gone since the start of the semester, the amount of info sprinkled on us is just overwhelming. Therefore, I decided to skip talking extensively about particular sample collecting, solution making, sterilizing procedures and protocols. However, this doesn’t mean I won’t be happy to sacrifice some posts to such things, if any curious readers turn up. We’ll see…

As an introduction: these guys live on my fingertips...
See what can live on your wristwatch?
 One can even notice the place of the battery...
Now, let me give you some proof on the existence of microbes. In our first class a task was to collect samples form our very environment, in order to check whether there is anyone alive in it. I don’t know what your university life is/was like, but imagine 16 biology students covered in green lab coats from head to toe spreading across corridors, bathrooms, stairways, basically all around the building. We were well armed, a couple of Petri plates in one hand and a pair of forceps installed with decent cotton balls in the other, plus a couple of cotton swabs. I guess we deserved to be called meticulous. We dumped our ’collectors’ into toilets, grids of the air conditioning system, collected samples from handles of certain rooms, from the sole of our shoes, etc. Also, not just our surroundings but ourselves were the subjects of this experiment. Many clothes, body parts, pieces of hair, personal goods such as phones, bracelets, wristwatches, and coins were in our focus.

Red algae, a source of the agar
The way of culturing bacteria is relatively easy, it means letting them grow in a place where further contamination with new species (who are not the ones we collected on the certain spot) is avoided. The Petri plate or culture dish is a lab instrument used since the late 19th century. A certain culturing medium is attached to its base; simply imagine a light brownish-yellowish jelly. This “jellyness” is usually acquired by the use of the substance called “agar-agar” which is prevalent in the cell wall of red algae. There are many medium types, some of them especially mixed for a certain species of bacteria, blocking all others to thrive on it. In our case, the use of such growth mediums is inefficient, as we were aiming to grow anything collected.

The procedure started with a simple touch on the surface we decided to gain the sample from with a cotton ball, open the dish, a quick stroke on the jelly, and close the plate again. It sounds stupid, telling all this, but leaving the dish open for only a couple of seconds is crucial, otherwise you might end up getting some unwanted fellows residing on your construct. Some of us turned to this very easy, however unexpectedly rewarding way of sample collection: they simply left their dish open for 5-10 min at a certain place. As the air is also a workplace for some microbes (they form the so called bioaerosol) these culture mediums weren’t left empty.

This tiny fellow seems like a castle, doesn't it? Such creatures are continually
changing their appearance, so this morphology is just a snapshot from its life.
For the evaluation of our work we had to wait a week. During this time, our plates were carefully kept in a room, which retains 28 Celsius day and night. The result was amazing, as you see below. The most shocking for me were the samples I collected from my hands before and after washing them. It seems I’m not as precise in that process as the group was in the collection. The result was disappointing, practically there was no significant difference between the two. The only thing relieving is that even the neatest girls in the group had some colonies of bacteria on their “washed hands” plate.

The characterization and defining of species of bacteria based only on morphology is quite hard. In our course schedule there is a class dedicated to this topic, so I refrain myself from giving it a try this time.
Some beautiful thready creatures right from a public toilet's seat.

1 comment:

  1. It is a really enjoyable piece of writing for an amateur, I liked the style of it!