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Microbiology Buying Guide

Carolina is here to provide everything you need to teach your microbiology labs. We have solutions that focus on lab skills and advanced college-level microbiology education. Choose from many relevant topics, including culture growth and identification, antibiotic resistance, and environmental sampling.

Want more assistance? Call our customer support team at 800.334.5551 and let our staff and technical experts help you find the products that fit your needs. Shop with confidence—all of our products are unconditionally guaranteed.


Carolina offers a large selection of cultures. From Chlorella to bioluminescent dinoflagellates, Aspergillus to Sordaria, we have what you need to fascinate your students and bring hands-on learning to your classroom. Our cultures are available in economical tube cultures, convenient plate cultures, or freeze-dried MicroKwik Cultures. Each culture contains enough material for a class of 30 students. We maintain a large inventory of cultures in stock for immediate delivery, so you can always depend on getting what you need when you need it. Our cultures are also available in kits and sets.


Bacterial labs frequently form the backbone of the microbiology class. Carolina has over 100 bacteria cultures. From evolution to food microbiology, bacteria support studies that relate to real-world applications. Find microorganisms that are safe and suitable for all skill levels.

Studying a variety of species is easy with our competitively-priced topic sets.

Archaea (Halobacterium)

The group of microorganisms known as Archaea offer many examples of extremophiles. Use Halobacterium to demonstrate a tolerance to high salt concentrations.

Did you know Carolina cultures are used for education and research at institutions all over the world—and even beyond? Check out this video of an experiment in space that uses Halobacterium from Carolina.

Fungi and Protists

The microbiome isn’t entirely prokaryotes. Fungi and protists make up an essential part of the microbial landscape. From Penicillium to Paramecium, we offer more than 60 fungal and protozoan cultures.

Fungi and protists play an important role in the treatment of diseases and in the production of antibiotics. Other eukaryotic microbes, such as Penicillium roqueforti and Saccharomyces cerevisiae, play important roles in food production.



Good microbiology labs start with good media. Don’t forget to order your culture media, culture media ingredients, and culture additives. We also provide pooled animal blood and plasma products that are ideal for virologic and serological work and for use in microbiological culture media. All our media products are free of antibiotics and pesticides. The media have been sterility tested and are quality assured. Not sure which media is right for you? Check out some of our media-focused digital resources for more information.

Dehydrated Media

We have a wide variety of dehydrated media to choose from. Our most popular choices can be purchased in 100-g and 500-g sizes. Using dehydrated media is the most cost-effective option since it has a long shelf life.

Media Ingredients

Making your own media is easy with our high-quality additives like pooled animal bloods, plasmas, and specific sugar substrates. Looking to create your own specialized media plate? Carolina has you covered! Contact us at 800.334.5551 if you don't see what you need.

Prepared Media

Using prepared media is a great way to save time in the lab. Our prepared media is available in tubes, broth, plates and melt-and-pour bottles. Prepared media tubes minimize the risk of contamination while extending the storage life of the media. Our melt-and-pour media bottles are convenient and easy to use. Just melt in a microwave or boiling water bath and pour your plates—no autoclave required! We also offer a variety of prepared media plates that have been tested for sterility and their ability to support the characteristic growth of appropriate organisms.


Equipment and Supplies

Get the high-quality equipment and supplies you need to create a safe and sterile environment for your microbiology labs.


Carolina offers convenient stain sets that are already prepared and ready to use. We supply large comprehensive stain sets as well as basic Gram stain sets to aid in the exploration of cell structure and classification.


Maintaining a sterile lab is key to a successful lab experience. Choose the autoclave or sterilizer that meets your lab or classroom needs. Sterilization is quick, easy, and safe! We have manual or automatic autoclaves and infrared sterilizers that can sterilize instruments in just 5 to 7 seconds. Sterilizers have asbestos-free ceramic core heater elements. We carry Carolina, Tuttnauer, and Wisconsin Aluminum Foundry brands.


We offer sterile, disposable inoculating loops which eliminate the need for open flame in the lab. Sterile cotton-tipped applicators are perfect for inoculating media. Easy to use colony counters allow you to accurately maximize your time in the lab.

Popular Labs

Below is a list of popular microbiology labs and some resources that Carolina has available to help support those labs. Procedures for several of these lab activities are available in our free guide Techniques for Studying Bacteria and Fungi. Many of the labs include reusable supplies.

Basic Techniques

Transfer techniques/ Aseptic technique

In The Introduction to Sterile Technique lab, students practice transfer of a bacterial culture using sterile technique. The lab is intended as an introductory microbiology activity. Before conducting the lab, ensure that students are familiar with standard lab procedures, including the use of gas burners and personal protective equipment (PPE).

Isolating Streak Plate

In the Isolating Bacteria from a Mixture lab, students are introduced to a basic technique used in the study of bacteria: isolating a single species of bacterium from a mixture. In this activity, students practice the technique by using a mixture of bacteria of known composition.

Bacterial Morphology

Students can view the different cellular morphologies using prepared slides, or they can learn how to prepare bacterial slides, perform simple stains, and observe bacterial cell shapes with the Introductory Bacterial Morphology Set. Either way, they will need a microscope with oil immersion, such as the Wolfe® LED Advanced Binocular Microscope. Use the Characteristics of Bacteria chart if you’d prefer to select your own array of organisms.

Combine environmental sampling with identification of colony characteristics using the Bacterial Investigative BioKit®.


Bacterial cells can be colored with a simple stain to provide contrast with the background. Differential stains, which are more complex than simple ones, are used to divide bacteria into groups. Bacteria stain differentially because they differ in cell wall composition. The Gram stain separates almost all bacteria into 2 large groups: Gram-positive bacteria, which stain blue, and Gram-negative bacteria, which stain pink. This classification is basic to bacteriological identification. Endospore stain selectively stains the endospore form of spore-forming bacteria and capsule stain allows visualization of capsules in the bacteria that secrete them.


The ability for bacteria to transfer genes between organisms has been an important factor in the development of several biotechnology tools and in the development of antibiotic resistant bacteria. The Introductory Bacterial Conjugation Kit is useful for teaching bacterial identification and the intercellular transfer of genes for antibiotic resistance between microorganisms. Students identify and confirm the identity of bacteria with different antibiotic resistance by streaking on different antibiotic selective media. Strains are then combined on a "mating" plate to allow conjugation. Results are tested on various media for growth response to demonstrate that DNA can be transferred between 2 genetically different cells.

Biochemical Tests

Biochemical tests can be used to distinguish between similar organisms.

Carolina’s Enteric Biochemical Detective Kit examines organisms for citrate utilization, hydrogen sulfide production, butanediol fermentation, and mixed acid fermentation.

In the Bacterial Biochemical Identification Kit students conduct starch, lipid, and protein degradation tests on the bacteria to detect the difference between 3 Bacillus species.


Bacterial Motility details how motility in bacteria can be tested for using either the hanging drop method, which requires a depression slide and a microscope, or by stabbing motility media. Motility tests can be combined with other tests such as SIM media which tests for sulfide production and the ability to decompose tryptophan to indole.

Sample Bacteria

Motility Test Results

Sulfide Production

Indole Formation
Bacillus cereus (+) positive (-) negative (-) negative
Escherichia coli (+) positive (-) negative (-) negative
Enterobacter aerogenes (+) positive (-) negative (-) negative
Proteus mirabilis (+) positive (+) positive (-) negative
Salmonella typhimurium (+) positive (+) positive (-) negative
Serratia marcescens (+) positive (-) negative (-) negative

Indole Test

In the lab Bacteria: The Indole Test, students perform a differential test to distinguish bacteria based on the production of indole. Bacteria are grown on media containing tryptophan and then treated with Kovac’s reagent. If they possess the enzyme tryptophanase, the bacteria can metabolize tryptophan into indole, pyruvic acid, and ammonia. Kovac’s reagent then reacts with indole to produce a red color that will be concentrated in a layer at the top of the media. In the absence of indole, Kovac’s reagent remains yellow.

Sample Bacteria

Motility Test Results

Sulfide Production

Indole Formation
Bacillus cereus (+) positive (-) negative (-) negative
Escherichia coli (+) positive (-) negative (+) positive
Enterobacter aerogenes (+) positive (-) negative (-) negative
Proteus mirabilis (+) positive (+) positive (-) negative
Salmonella typhimurium (+) positive (+) positive (-) negative
Serratia marcescens (+) positive (-) negative (-) negative

Methyl Red/ Voges-Proskauer

Using the MR-VP Test Kit on bacteria grown on MR-VP media, students can test for several metabolic pathways. The Methyl Red (MR) test is positive for organisms that convert dextrose and glucose to pyruvate along a mixed acid pathway, resulting in acidic end products such as lactic, or formic acid. If the organism uses the butylene glycol pathway or another pathway with unstable acidic products, the culture will turn yellow. The VP test detects organisms that produce acetoin via the butylene glycol pathway. A red color is produced in the presence of acetoin and a copper color is produced in its absence.

Sample Bacteria


Escherichia coli (+) positive (-) negative
Enterobacter aerogenes (-) negative (+) positive
Serratia liquefaciens (+) positive (+) positive

Citrate Test

Bacteria: The Citrate Test outlines how students perform the citrate test. This test determines if organisms can use citric acid as their sole carbon source. The citrate test is often performed as part of the IMViC (Indole, Methyl Red, Voges-Proskauer, and Citrate) series of tests used to differentiate common species of enteric bacteria.

Sample Bacteria

Citrate Test Results
Citrobacter freundii (+) positive
Enterobacter aerogenes (+) positive
Escherichia coli (-) negative
Klebsiella pnemoniae (-) negative

Carbohydrate Fermentation Durham Tubes

Phenol Red Broth can be used with a variety of sugars to identify whether organisms can metabolize the sugar substrate. If the organism produces an acid by-product during fermentation the phenol red will turn yellow. If a gas by-product is produced a bubble will form in the immersed Durham tube.

Sample Bacteria





Bacillus cereus (+) positive (-) negative (+) positive (-) negative variable
Proteus mirabilis (+) positive (-) negative (-) negative (-) negative (-) negative
Salmonella typhimurium (+) positive (-) negative (+) positive (+) positive (-) negative
Serratia marcescens (+) positive (-) negative (+) positive (+) positive (+) positive
Staphylococcus epidermidis (+) positive (+) positive (+) positive (-) negative (+) positive

Blood Agar Test

Blood agars can be used to determine the hemolytic capabilities of a bacteria culture. If the organism can break down hemoglobin completely, they will leave a clear zone surrounding the bacterial growth. Partial breakdown will leave behind a greenish color.

Sample Bacteria

Streptococcus pneumoniae alpha hemolysis (incomplete)
Streptococcus pyogenes beta hemolysis (complete
Staphylococcus epidermidis gamma hemolysis (non-hemolytic)

Selective and Differential Media

In Bacterial Growth on MacConkey Agar, students culture 3 bacteria on nutrient agar and MacConkey agar and record the results.  MacConkey agar is both a selective and a differential media. Crystal violet and bile salts inhibit most Gram-positive bacteria, allowing Gram negative bacteria to grow. The presence of lactose and a pH indicator which differentiates between species that can use lactose and those that cannot. Those that can metabolize lactose produce an acid and change the color of the agar from red to pink.

Sample Bacteria

Gram -/+

Lactose Fermentation
Bacillus subtilis + No growth
Escherichia coli - (+) positive
Pseudomonas fluorescens - (-) negative

Like MacConkey agar, mannitol salt agar is both selective and differential. The high salt concentration favors halophiles, while the use of the sugar mannitol as a fermentation substrate will cause the pH indicator Phenol Red to turn the agar yellow in the presence of an organism that can ferment mannitol.

Sample Bacteria

Mannitol Fermentation
Staphylococcus aureus (+) positive
Staphylococcus epidermidis (-) negative

Eosin methylene blue agar is selective for Gram-negative bacteria. Depending on the strength of fermentation on sucrose and lactose, the indicators eosin Y and methylene blue will turn the growing colonies purple in moderate to vigorous fermenters. Sometimes a green metallic sheen will form in the presence of vigorous fermenters such as E. coli. Weak fermenters will produce pink colonies. Non-fecal coliform bacteria will be colorless or its normal color.

Sample Bacteria

Gram -/+

Lactose Fermentation
Bacillus subtilis + No growth
Enterobacter aerogenes - (+) positive (weak)
Escherichia coli - (+) positive (strong)
Pseudomonas fluorescens - (-) negative

Medical Microbiology

Carolina BioKits®: Antiseptic Versus Disinfectant Sensitivity Kits enable students to discover through experimentation the relative effectiveness of 5 common disinfectants and antiseptics on Escherichia coli, a Gram-negative bacterium, and Bacillus cereus, a Gram-positive bacterium.

The Carolina Antibiotic Production Kit demonstrates the production of 2 antibiotics: penicillin by a fungus and streptomycin by a bacterium. The inhibitory effect of these antibiotics on the growth of a Gram-positive bacterium and a Gram-negative bacterium are observed. Students can visualize the interrelationships of these microbes and understand how humankind has used microbes to produce our antibiotics.

You can also use antibiotic disks to test sensitivity to a range of antibiotics.

Bring real infectious disease testing into your classroom safely with The Tragic Case of Stan. Created by scientists at the Center for Translational Science Education at Tufts University, this unique kit provides students with a robust learning experience that addresses a real medical problem facing hospitals around the world.

Food Microbiology

Humans have managed food spoilage in a wide number of ways. We have kits that examine the effects of salt, sugar, spices, and chemical preservatives on microbial growth.

Environmental Microbiology

Microbes are everywhere, and there are many options for exploring the roles that they play in the world around us. From drinking water contamination to microbes’ role in nitrogen cycling, Carolina provides kits and resources to help address the ubiquity of microbial life.