Low-Tech Microbiology Tools

You don't need a lab full of fancy tools and glassware to do molecular biology. Electric fifth burners, for example, cost about $15 and work just as well as laboratory hot plates, which cost hundreds of dollars. And paper plates and plastic spoons work just as well as laboratory weigh boats and spatulas.

Use your imagination!

Molecular biologists use spreaders to evenly distribute samples across agar plates. You can buy fancy glass spreaders for about $5 each, or you can make your own for much less.

Pasteur pipet spreaders

1. Heat the tip of a long–nose glass Pasteur pipet in a flame until it melts and seals itself.
2. Heat the narrow portion of the pipet about 2 inches from the tip. When it melts, gravity should take over, bending it down at a 70-90 degree angle. If it doesn't bend on its own, you can push the pipet gently against a solid surface.
3. To sterilize, store in a beaker of alcohol. Before use, pass it through a flame to burn off excess alcohol.

Paperclip spreaders: Straighten a large size paperclip to make an "L" shape. Wrap in foil and sterilize in an autoclave or an oven; or dip into a container of alcohol, or heat in a flame before use.

Toothpicks, coffee stirrers, and wooden craft sticks These don't work quite as well as other spreader tools because their rough edges tend to scratch agar plates. But they are fairly effective for spreading larger volumes of liquid. Place in envelopes, foil, or glass test tubes and sterilize in an autoclave or an oven before use.

Molecular biologists use inoculating loops for picking up single colonies and streaking samples across a plate. At about $3 each, inoculating loops are inexpensive; but here are some options that cost even less.

• Wooden craft sticks and coffee stirrers are good disposable alternatives to inoculating loops. Put them into envelopes and sterilize them in an autoclave or an oven.
• Wooden toothpicks work pretty well, although their shorter length makes them a little more challenging to work with. The main advantage of toothpicks is that they are sterile in their boxes.

Molecular biologists use autoclaves for sterilizing their media and materials. But pressure cookers are an inexpensive and very effective alternative. Just like an autoclave, the pressure cooker chamber reaches temperatures high enough to kill contaminating bacteria and mold spores.

Pressure cookers come in a variety of sizes and configurations; those designed for canning tend to be the largest. Electric models are convenient if you don't have a burner or a hot plate, but they tend to be shorter than stovetop models, making them suitable only for smaller amounts of material. Choose a pressure cooker large enough to hold your containers.

Learn more about sterilizing liquids and solid objects.

Molecular biologists typically use Bunsen burners to create a flame for sterilizing microbiology tools (such as inoculating loops), burning off sterilizing alcohol from spreaders, and flaming bottle mouths to keep them free of contaminants. If you don't have access to a Bunsen burner, the following flame sources will serve you just as well.

• Plumber's torches (also called soldering torches) cost about $25 for smaller models.
• Camping stoves are convenient if you happen to have one on hand—just make sure you use them in a properly ventilated area.
• Gas stove burners are readily available in many homes. They're perfect for "kitchen scientists."
• Alcohol burners are sufficient for standard molecular biology work even though they do not burn as hot as other types of flames.
• Sterno cans or fondue gel, both of which are ethanol based, produce clean, hot flames at bargain prices.
• If you sterilize your tools in alcohol, lighters and candles work for burning off the excess.

Molecular biology labs are usually stocked with an assortment of glass flasks, beakers, and bottles. Scientists use them for preparing media and other sterile solutions, as well as for holding liquid bacterial cultures. Laboratory glassware is great because it holds up well on hot plates and in autoclaves, but glassware from your kitchen can work too, and for a fraction of the cost.

Glass food jars or canning jars hold up well in pressure cookers and microwaves—just be sure to remove metal lids and cover with plastic wrap before microwaving. Remember, however, that glass food jars are not safe for use on hot plates. Direct contact with a heat source may cause them to crack or shatter.

Empty baby food jars work well for collecting water samples. Some people even use them in place of Petri dishes. Wash the jars and lids well and sterilize them before use. Put the lids on loosely or cover the jar openings with aluminum foil, then sterilize them in your pressure cooker, oven, or autoclave (see the Sterilizing Solid Objects page).