Important tools of microbiology: Garbage bags by Christina Kellogg

CK in garbage bag darkroom, credit Stéphane HourdezThe Hitchhiker’s Guide to the Galaxy advises that it is always useful to have your own towel. Sea-going microscopists are similarly advised to bring a large black garbage bag and duct tape.

Viral particles are very small, often less than 200 nm. For perspective, the diameter of a human hair is about 50,000 nm. In the past, the only way to see and count marine viruses was by using a transmission electron microscope (TEM), an expensive and complicated device that uses electrons instead of light to visualize small objects. However, fluorescent dyes have been developed that emit very bright light and these dyes can be used to stain the DNA inside the viral particles. Even though the viral particles are small, the light emitted is bright enough to make them detectable–under a portable fluorescence microscope at 100x magnification, the effect is like counting stars in the night sky. Obviously, the darker the background the easier it is to see the tiny pinpricks of light. This type of work is typically done in a darkroom. Most ships do not have a darkroom. I think you can see where the garbage bag and duct tape come in…they are all you need to construct your own personal darkroom.

Epifluorescence photomicrograph of bacteria (planets), viruses (distant stars) and a pennate diatom (galaxy), credit Jed Fuhrman
To read more about viruses in the deep-sea and how they control the genetic diversity of bacterial communities and carbon cycling, please visit the July 1 daily log from the Deep Slope Expedition 2007