Field of Science

Showing posts with label contamination. Show all posts
Showing posts with label contamination. Show all posts

Pictures of my microbes

I'm usually very reluctant to put my own work on this blog, as none of it has yet been published. Depite the CC logo at the bottom of the page I'm still very much aware that anything you put on the internet can potentially be taken away and used for nefarious purposes, without acknowledgement. Also I really don't want to 'out' any of my research.

But this is so amazing I had to share it. It's from the control of a failed experiment anyway, so shouldn't be giving too much away. It's taken with a light microscope, and shows a species of Streptomyces bacteria (complete with contamination):

I feel very proud of that picture, and not only because it took ages fiddling around with a microscope and two broken slides (don't ask!) to produce. The big blob in the middle is the Streptomyces, but it's not one Streptomyces bacteria it's a whole network of integrated hyphae; long branching filamentous cells. This can be seen particularly well in the largest blob in the middle, which has a filamentous 'tail' like structure coming out of it, these are the mycelium branching out and breaking away. Some of them will branch off completely as single cells, and differentiate to form spores.

If you look up at the top right hand corner of the picture, you can just about make out some little dark dots. These are E. coli! My sample is clearly contaminated, those little dots were actually wriggling around under the microscope which made it look slightly freaky. Although the contrast in the picture doesn't show it, the little wriggling E. coli are pretty much everywhere, surrounding the larger Streptomyces structures.

My PI was shaking her head and going "Oh dear, it's all contaminated" but I was just staring into the microscope, fascinated at the amazing world presented inside it. It was like that bit in 'The Borrowers' when The Boy peeks under the floorboards and sees a world full of little people, a whole universe of life which he never knew existed. I went a bit mad taking pictures:

The picture above is a closeup of the hyphae, at a higher magnification. You can make out individual threads, which are formed by long thin cells growing forward in a line. This picture shows the meeting point of three different Streptomyces colonies and an area which is miraculously free from contamination.

In a way, I think I preferred seeing the contamination, despite the fact that I now have to grow the things all over again. It was a reminder that the bacterial world isn't just a collection of similar shaped blobs floating around together. Seeing this little snapshot of the Streptomyces in their huge hyphae fortresses surrounded by little scurrying E. coli reminded me that the bacterial world is as diverse in size and shape as the animal one, just on a far smaller scale. In fact, biochemically, it's more diverse than the animal world and just as dangerous.

Anyway, now I have to stop gushing and go do some actual work :)

Contamination!

I came in this morning, all bright and ready for phage propagation (harvesting phages from plates is actually quite fun) and what did we find? All the plates from yesterday were bad. To make a phage plaque you plate out a smooth 'lawn' of bacteria onto an agar plate and then pour phage over it. Where one phage lands it kills and multiplies until it forms a little clear spot or 'plaque' on the plate. (you can't see the phage plaques very well in the picture, but you can see the bacterial lawn)

This morning, all our plates had little fuzzy marks on them. Which is fine, could be phages except...so did the control plate. The control plate had no phage on it at all, it was meant to have just the bacteria but itstead it too had little fuzzy marks.

*sigh*

Without good controls you can't trust your results. At first we thought it was just badly grown host until my supervisor noticed that the tryptone we'd been working with (tryptone broth is one medium that you can grow the bacteria in) was cloudy. Not good. If a substance that is usually clear starts looking cloudy then it means it's got bacteria in it.

Our plates were all contaminated. The fuzzy marks were phage, bad host and/or another bacterial contaminant. Basically we have to do all of yesterdays work all over again today and we need a lot more media (agar for plates, tryptone for bacteria, etc).

Guess who gets to make up all the new media?

I do love working in labs. But it can sometimes be the more frustrating thing on earth. And media pouring is just mindnumbingly boring and faintly awkward. Which is why, of course, the lab rat gets to do it.