From "The Amateur Scientist"

FOR CITIZEN SCIENTISTS AND EXPERIENCED STUDENTS: Here are some microbiology projects from  The Amateur Scientist  

1. "About Cultivating Algae From the Soil and Making Steady Telescope Mountings,"  December, 1954
2. "How to Cultivate Harmless Bacteria and Perform Experiments with Them," March, 1958  [Note: If you want to work with potentially dangerous organisms, you'll need an "aseptic transfer chamber" to process your cultures safely.  This article describes how to construct one.]
3. "Experiments in Phototaxis: the Response of Organisms to Changes in Illumination,"  October, 1964
4. "How to Study the Genetics of Fruit Flies with Chromatograms Viewed By an Ultraviolet Lamp," June, 1965
5. "How to Isolate From Samples of Topsoil Microorganisms That Secrete Antibiotics," November, 1965
6. "How to Cultivate the Slime Molds and Perform Experiments on Them,"  January, 1966
7. "Antigens and Antibodies Are Studied By Their Diffusion Patterns in Agar," September, 1969
8. "Genetically Altering Escherichia Coli," June 1994 (advanced!)
9. "The Pleasures of Pond Scum," March 1998
10. "Spooling the Stuff of Life," September, 1998  [Note: Today, millions of school children extract DNA from strawberries every year. This was the article that first  published the secret of extracting DNA using simple kitchen chemistry.]
11. "PCR at Home," July, 2000
12. "How to Rear a Plankton Menagerie," August, 2000

XXX   COACHING PROGRAM--SAS members only. 

If you're new to science projects and you  want to experiment with mold, bacteria, or fungi, I recommend you start with the Complete Microbiology Kit below.  It comes with 10 sterile Petri dishes with a nutrient  agar growth medium already installed, plus just about everything else you need to carry out most experiments of the type you are about to do.  Remember KYSS--Key Your Science Simple! Pre-poured petri dishes plus  everything else you're going to get with this package will certainly make your project much simpler and help guarantee your success.  And success here will help give you the confidence you need to tackle more difficult challenges going forwards. 

You will still need to sterilize your workspace and to disinfect your used petri dishes after your experiment is done before you seal them in a zip lock bag and put them in the trash. You could use bleach (see PROTIP below), or better, use either a Glutaraldehide disinfectant or a Quaternary Ammonium cleaner (also known as a "Quat" disinfectant).  (See SAFETY EQUIPMENT below for both.) Whenever working with microbes, you need  Nitrile gloves and eye protection to stay safe. If you're growing mold or any other fungus, you should also wear a facemark to prevent  breathing in any spores which might want to colonize your lungs. (That's not likely, but better safe than sorry.) Make sure you wear long sleeves to protect your arms and put your cloths in the washing machine as soon as you step away from your lab. And while it's not essential, remember that microbiologists wear lab coats for a reason!    

If your experiment requires microbes to be transferred from one Petri dish to another (and many experiments do), or if you need to purify a wild sample of microbes so that you end up a single strain, you'll need to purchase an inoculation loop. 

By the way, if you're looking for a source of safe bacteria to grow, look no farther than you own mouth. Since the bacteria that live inside you don't make you sick, they are safe to grow in your Petri dishes. 

Finally, if you would like to purchase a microscope for your experiments, check out our General Lab Supplies. 

PROTIP:  If you want to use chlorine as a sanitizing agent, for best results start with granular chlorine. Dissolve as much of the solid as possible into 30 milliliters (about an ounce) of warm water. Then prepare a 10-to-1 dilution by mixing five milliliters (one teaspoon) of the concentrated chlorine solution into 45 milliliters of distilled water.  If you need to prepare water to be used in a growth medium, add three drops per liter of solution to sanitize. Leave the container open and wait 2 hours for the chlorine to do its work. Then, either aerate by bubbling HEPA-filtered (0.2 micron) air through it for another 24 hours to evaporate the poison from the liquid, or neutralize it in seconds using a dechlorinating agent of the type sold at fish stores. Either way, don't introduce microbes into sanitized medium until you've verified, using a kit for testing home pools, that no chlorine is detectable. 

COMPLETE SCIENCE KIT: [From the manufacturer...] "Start your science experiment journey with our kit, complete with 10 pre-poured agar plates, 10 cotton tipped sticks, 1 pipette, 1 plastic vial to be used in experiments, simple-to-follow instructions, and an informative science experiment ebook project guide. This product is intended for ages 15 years and older. 

• RELIABLE & SECURE: Experience the height of science education with our kit, created for educational purposes. These agar plates include a thick agar layer, that are ready to use for your experiment. The customized packaging are more durable than conventional solutions. 
• CONVENIENTLY PRE-POURED FOR EASY USE: Our pre-poured, ready-to-use nutrient agar petri dishes eliminates the need for technical agar melting and pouring. Our skillfully concocted plates facilitates proper agar consistency and thickness. 
• THE EXPERIMENT EBOOK: Get creative and think of thrilling ideas to experiment in the classroom with our science kit that includes an exciting experiment ebook. The eBook is filled with simple experiments that come with clear step-by-step instructions to help you succeed! 
• WE VALUE CUSTOMER SATISFACTION: We believe that you will enjoy your science fair project kit and would even suggest it to your acquaintances. However, if you are not entirely satisfied with it, please let us know and we will make things right."

Inoculation loops are essential tools for purifying strains of microbes. The loop captures a clump of cells from the surface of the agar in a Petri dish. When rapidly streaked across a fresh batch of agar, cells fall from the loop in tiny clumps, which tend to be less diverse than the whole. These clumps grow up in small circular colonies. Repeating the process with one of these colonies, creates new colonies with even fewer cell types. After a few iterations, you'll be growing pure strains of something. This is the process that researchers typically use to purify cell lines, so they can study a single species. 

This set of loops is a great starter set. A loop must be placed in a gas flame or the flame of an alcohol lamp and heated to red-hot temperatures to sterilize it just before using it to grab a sample. (A lighter or flame from burner of a gas stove will work as well.) If you use an alcohol lamp, you'll also need denatured alcohol for fuel. 

A dedicated citizen scientist can do great things in microbiology. One can, for example, search for new antibiotics by safely cultivating wild strains of bacteria. (See project #5 from the list above, November 1965.) One can also evaluate local algae strains as potential sources of food stocks or biofuels. ("How to Rear a Plankton Menagerie," August 2000) 

Citizen scientists who want to get into this field should invest in the right equipment. Ordinarily, one should be wary of plastic Petri dishes because they tend to crack after a few cycles in the sterilizer.  The exception to that rules is the autoclavable plastic Petri dishes listed below. So consider those if they meet your needs. Many researchers prefer glass, so I've included a link to purchase lab-grade borosilicate glass Petri dishes as well. You'll certainly need nutrient agar for your growth medium. You'll also need inoculation loops if you want to purify your microbe strains or otherwise transfer samples from one Petri dish to another.  You will also need Erlenmeyer flasks to process the agar and poor it into the Petri dishes, as well as sterile cotton to plug the flasks.  

If you're growing microorganisms in Erlenmeyer flasks, in addition to plugging them with sterile cotton, you can cover the mouth by placing an oversized square of aluminum foil over the top of the lid and then pressing the edges down around the neck.  This doesn't stop gas exchange, but it will reduce the risk of contamination.  After cleaning and sterilizing their glassware and allowing it to cool in the autoclave, professional researchers  immediately cover the mouths of their beakers and flasks to prevent airborne bacteria from falling in between uses.  They use aluminum foil  or, when  they want to seal it completely,  Parafilm.  You can, and probably should, too.  

If you're going to be growing up big batches of microorganisms such as algae, you'll need large carboys. A few years after my August, 2000 article on the topic came out, researchers discovered that plastic carboys tend to suffer tiny scratches when they are scrubbed clean, and that these scratches made perfect homes for unwanted bacteria. So the industry switched to glass containers instead.  If I wrote the article today the picture on the left would show a 6-gallon glass carboy and either 2-liter Erlenmeyer flasks, milk bottles, or 1 gallon fermentation bottles, all with rubber stoppers. (Search Amazon for stoppers to fit whatever bottles you decide to buy.)

Sea water kit ... salinity tester kit ... 

XXX

You want to keep your cultures out of direct sunlight because the sun can heat them to lethal  temperatures.  Instead, you'll want to install GROW LIGHTS on and keep them one for 18 hours per day using a shut off timer.

Order algae and rotofores. 

Supply nutrients

You'll need to aerate your your cultures. A simple aquarium pump, a manafold, and aquarium tubing will get the air into your system.  You'll also need a 0.2 micron hose filter to screen bacteria out of the air. I used to use this Millipore Syringe filter , and while they typically cost under $20 each, they are sold in sets of 10.  However, since my last explorations in this area far less expensive options have hit the market.  While these filters are not sterile when they arrive,  it should be possible to sanitize them with a glutaraldehyde or quat disinfectant, but I haven't tested it.  If you test these less expensive filters out, please let me know what you discover.  

PRO TIP: By the way, if you need to cut a bung hole in a rubber stopper, here's how to do it. Just get a short length of stiff copper tubing that's the diameter you want your hole to be. Then sharpen one edge of the tube by pressing it at an angle against a grinding wheel. That's your drill. Then chuck the dull side into a drill press, add some lubricant, and drill at low speed until you cut through the stopper. 

Autoclavable Plastic Petri dishes-10 pack

From the manufacturer:

• "Food-grade material, exceptional heat and impact resistance, flame retardancy, and high refractive index. Unlike other plastic culture dishes (melting at 122℉/50°C), ours withstand sterilization up to 250℉/121°C. With 99% light transmittance (PP5 dish being semi-transparent, only have a light transmittance of 40%), they excel in scientific research, offering durability, scratch resistance, and optimal sterilization at high temperatures. 
• Package: Sterile Plastic Petri Dishes: 10 Pack of 90mm diameter x 15mm deep Sterile Petri Dishes with Lids.【This model is a PC petri dish, which can sterilization up to 250℉/121°C, It's crucial to avoid using metal pots during sterilization to prevent melting since metal has higher thermal conductivity than water. The dish can withstand up to 15 PSI without melting as long as they are not in contact with a metal pot】 
• 3 Vented Lids: Each petri plate has 3 lids so that there is improved air circulation and less condensation, Ideal for growing bacteria, mold, yeast, fungus and other organisms."

Glass petri dishes: These culture dishes are great for all research projects. Available in 60mm, 100mm, and 120mm diameters.  Made of lab-grade borosilicate glass, with lids.   

Nutrient Agar:  Essential for all microbiology experiments, and many that involve sprouting seeds.  This brand is easy to use. Make sure to autoclave it before pouring it into sterile Petri dishes. 

Inoculation loops are an essential tool for purifying strains of microbes. The loop captures a clump of cells. When rapidly streaked across a fresh batch of agar, cells fall from the loop in small clumps, which tend to be less diverse than the whole. These clumps grow up in small circular colonies. Repeating the process with one of these colonies, creates new colonies with even fewer cell types. After a few iterations, you'll be growing pure strains of something. This is the process that researchers typically use to purify cell lines, so they can study single species of microorganisms. 

This set of loops is a great starter set. A loop must be placed in a gas flame or the flame of an alcohol lamp and heated to red-hot temperatures to sterilize it just before using it to grab a sample. (A lighter or flame on a gas stove will work as well.)

Erlenmeyer Flasks are a must for almost any laboratory. XXX This link will take you to a great deal son three different sizes of Erlenmeyer flasks that would be appropriate for this work, and more!   

You'll need sterile cotton to plug your Erlenmeyer flasks while processing your agar. 

6 gallon glass carboy . 1 gallon fermentation flasks XXXI d to plug your Erlenmeyer flasks while processing your agar. 

Grow lights  on a shut off timer. 

Glass carboy . I d to plug your Erlenmeyer flasks while processing your agar. 

Because they sell relatively few copies and only to professional who need them, technical trade textbooks can cost many hundreds of dollars.  Sp citizen scientists on a budget are well advised to find older titles that have been eclipsed by later versions.  The following texts are reasonably priced and are jammed full with invaluable secrets of the craft. 

•  Manual of Clinical Mycology Norman Conant,   An excellent general manual on cultivating and identifying fungi, first public in 1945 and updated at least through 1971. 
• Plankton Culture Manual by Frank Hoff and Terry Snell, which is a definitive manual on cultivating both phyto- and zooplankton. 

MetriCide-Glutaraldehyde Cold Sterilization Solution  (1 gallon) BETTER THAN BLEACH This disinfectant is used by hospitals and research labs the world over. This highly effective sanitizing agent is ideal for citizen scientists and school-based experiments.  Included Components: Metrex 10-2800 Metricide 28 High-Level Disinfectant/Sterilant.  As you should with all chemical disinfectants, make sure to wear Nitrile Gloves when using this product. 

Quat Disinfectant (1 gallon) BETTER THAN BLEACH This disinfectant is also used by hospitals and research labs the world over. It kills via a different mechanism than Glutaraldehyde, but is just as effective. As always, make sure to wear Nitrile Gloves when using this product. I've included both disinfectants here merely for completeness, as they are both used widely in the industry. You need both. 

An autoclave is a pressure vessel that uses superheated steam to obliterate all microbes and their spores.  Many stove-top pressure cookers can be used as inexpensive autoclaves for the home experimenter or school lab.  This particular unit is inexpensive and makes sterilizing lab equipment easy for students and amateur scientists.  

NOTE: Whenever autoclaving growth medium or any other liquid, wait until the temperature of the pressure cooker has dropped  below the boiling point of water (100 degrees C) before venting the pressure. If the liquid is above that temperature it will boil over when you release the pressure, which will make you a very unhappy experimenter! 

Nitrile Gloves are essential for this work. Buy two boxes so you won't run out.  

Lab Coats are essential for serious research in microbiology. They keep all contaminates off your cloths, and their tight weave cotton fabric makes them surprisingly flame resistant. That's a great feature if you're flame-sterilizing inoculation loops that you are holding in your hand (which tends to stay close to your sleeves). If you're serious about this hobby, buy two lab coats so you will never have an excuse not to ware one. 

Face masks : It's a good idea to wear a fast mask if you're working with fungi, which can release spores into the air. If you're intend to do that lot, you should consider buying or building an "aseptic transfer chamber" (also known as a "glove box") as described in The Amateur Scientist column "How to Cultivate Harmless Bacteria and Perform Experiments with Them," March, 1958 . 

Lab Safety Goggles: Another "must-have" for this work.