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

Dr. M (1746 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, a National Science Foundation supported initiative. He has conducted deep-sea research for 20 years and published over 50 papers in the area. He has participated in and led dozens of oceanographic expeditions taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses on how energy drives the biology of marine invertebrates from individuals to ecosystems, specifically, seeking to uncover how organisms are adapted to different levels of carbon availability, i.e. food, and how this determines the kinds and number of species in different parts of the oceans. Craig’s research has been featured on National Public Radio, Discovery Channel, Fox News, National Geographic and ABC News. In addition to his scientific research, Craig also advocates the need for scientists to connect with the public and is the founder and chief editor of the acclaimed Deep-Sea News (, a popular ocean-themed blog that has won numerous awards. His writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web. His forthcoming book, Science of the South (, connects cultural icons of South such as pecan pie with the science behind them.

2 comments on “Important tools of microbiology: Garbage bags by Christina Kellogg
  1. I think that picture (or something similar, I’m sure I have a few on my work computer) needs to be added to my screen saver. That is, if I ever decide to give up on the squids.


Comments are closed.