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05 March 2004

Science Notebook: Getting Started in Microbiology

Forrest M. Mims III, Editor

Tim Davis's letter in the 27 February 2004 installment of "Backscatter" had an almost immediate reaction. In the first few hours after Sheldon Greaves posted the issue on the SAS web site, several readers sent letters asking for more information about microbiology.

Although my daughter Sarah and I are not trained biologists, we have had excellent results culturing and studying airborne bacteria using simple methods.

Sarah's bacteria research led to her original discovery of large numbers of bacteria and fungal spores in smoke from biomass fires in Yucatan arriving at our place in Texas. Her findings were recently published as the lead paper in a leading peer-reviewed journal (Sarah A. Mims and Forrest M. Mims III, Fungal spores are transported long distances in smoke from biomass fires, Atmospheric Environment 38, 651-655, 2004).

My microbiology studies have included informal studies of the effect of solar ultraviolet on Escherichia coli and Serratia marcescens in water. I have also conducted a formal study on changes in the ratio of nonpigmented bacteria to total bacteria in Brazil during the burning season. Results of this study suggest that the significant reductions in UV-B caused by severe smoke pollution can enhance the survival of nonpigmented bacteria that lack protection from normal levels of UV-B.

These experience in sampling and culturing bacteria have greatly increased my interest in microorganisms in the natural environment. As Tim Davis suggests in his letters in "Backscatter," this is an ideal topic for serious students and citizen scientists alike.

Student microbiologists

Every year many students around the United States and elsewhere conduct many kinds of microbiology studies. Some are highly sophisticated projects in molecular biology conducted in university labs under the supervision of Ph.D.-level scientists.

Others are simple projects about the presence of bacteria in everyday life. It's these kinds of studies that Tim Davis wrote about. Often these studies are much more interesting to a general audience than specialized molecular biology projects. That's because most of us have experienced gastric distress, skin infections and illnesses caused by bacteria in our environment.

Like many students elsewhere, students at Seguin High School in Seguin, Texas, have excelled in a wide variety of studies involving bacteria encountered in everyday life, and recent years have been especially fruitful year.

Gail Henry earned many awards for "Simple Protocol for Biofilm Reduction." This outstanding project provides a practical protocol that dentists can use to sterilize their water lines to eliminate bacterial contamination.

Heather Hines continued an equally professional 3-year study of bacterial contamination of water fountains at public schools in "Campus Drinking: Is there a Problem?" This first place project found that a low chlorine level in a public water line can permit the survival of dangerous levels of pathogenic bacteria.

These students are now in college, and they have been followed by other students at Seguin High School who are studying bacteria on everyday surfaces and in local bodies of water.

Safety considerations

Microbiology studies like these require safety precautions, for a single bacterium cultured on agar can blossom into a colony of millions of bacteria. It is possible that highly dangerous pathogenic bacteria can be captured and cultured on agar or alternative nutria media such as 3M Petrifilms. Thus, contamination must be avoided. Food and drink should not be consumed while working around bacteria cultures. Following study, cultures must be destroyed in a kind of pressure cooker known as an autoclave or by immersion in a disinfectant solution.

Because of the hazards associated with studying bacteria, some science fair competitions require very strict safety precautions and careful supervision. The rules of the Intel International Science and Engineering Fair (ISEF) require that students doing microbiology projects have their projects approved in writing by a Ph.D. scientist. Other major competitions have no such rules.

In my opinion, the ISEF rules are much too strict. They ignore the fact that classroom biology teachers without Ph.D.s have been trained to teach their students how to culture and study bacteria. Yet these teachers are not allowed to approve microbiology projects, even though they may be teaching hundreds of classroom students how to culture and study bacteria.

In any event, serious students and citizen scientists can safely study bacteria in their natural environment if they carefully follow appropriate safety and disposal procedures. Of course students should always consult with their parents and teachers before beginning an independent study of bacteria. Citizen scientists without microbiology experience should become familiar with basic microbiology methodology before beginning to culture specimens.

Resources for the aspiring citizen microbiologist

Many books have been published on this subject. Another source is some of the installments of "The Amateur Science" column in Scientific American. A good example is "Genetically Altering Escherichia Coli" by John Iovine (June 1994). You might be able to find this in a library, but a much better approach is to order from the Society for Amateur Scientists "The Complete Collection of The Amateur Scientist on CD-ROM." This CD includes every installment of "The Amateur Scientist." The package comes with a second CD entitled "Science Software Library," which is loaded with many practical science facts, hints, methods and ideas.

The web has many resources, and you can find considerable information by entering key words for the topic of interest in an Internet search engine. Typing the keywords bacteria open bodies water at www.google.com yielded more than 200,000 hits. More specific terms will reduce the number of hits.

The web has many sites that discuss how to culture bacteria. Some manufacturers and distributors of agar preparations have excellent literature on studying bacteria. For example, for information on culturing bacteria colonies on agar plates, see Ward"s Scientific's "Working with Bacteria" at http://wardsci.com/pdf/Working_with_Bacteria.pdf.

3M Petrifilms (TM) are very convenient plastic films coated with a thin layer of nutrient material. The media must be hydrated with sterile water prior to use. A transparent cover film is temporarily pulled away for hydration and to expose the nutrient media for inoculation. The cover film is replaced for incubation. For more information, see http://www.3m.com/microbiology/home/products/petrifilm/pp_biblioplate_legal.html.