Microbiology Laboratory Instruments

Microbiology is the study of life forms too small to see with the naked eye, or microbes. Bacteria, virus particles and many fungal species are all included in a vastly diverse microscopic world. Researchers who study microbes utilize instruments that allow growth, identification and description of microscopic living organisms. It is essential to have the capability to isolate different species and strains without contamination from other microscopic organisms. For example, a bacterial culture can become contaminated with other bacteria, viruses or fungi capable of destroying the desired culture.

Basic Microbiology Instruments

• Basic equipment utilized in the microbiology lab allows researchers to provide an environment in which bacteria and other microbes can be grown without threat of contamination. Microbes are generally grown in a liquid nutrient media called broth or on a gel material called agar. Cultures grown on agar are often maintained in covered plastic vessels called petri dishes. Broth can be used in a variety of plastic-ware, including test tubes or bottles. A small wire loop called an inoculating loop is often used to transfer bacteria from one media to another. Researchers will sterilize the inoculating loop between each transfer using a gas flame Bunsen burner. Although glassware can be used, plastic is preferred because it can be easily disposed of following test procedures.

Incubators Optimize Temperatures for Culture Growth

• Bacteria and other microbes grow better when maintained at optimal temperatures. Therefore, microbiology laboratories are generally equipped with an incubator. An incubator is similar to an oven and more capable of maintaining a fairly constant temperature. Many bacterial species grow optimally at 37 degrees Celsius, 98.6 degrees Fahrenheit. This is the same as body temperature found in normal humans. Bacterial species found in soil samples generally prefer a cooler growing temperature around 25 degrees Celsius. It is important for researchers to maintain a contaminant-free environment inside the incubator by aseptic cleaning after each use.

Viewing Microbes with Light Microscopy

• The cell shape of microbes can be viewed under a light microscope.

  A light microscope is another valuable piece of equipment used in a microbiology laboratory. Bacteria and fungal spores are very small and difficult to see, even with the maximum 1,000x amplification of a light microscope. However, this amplification is generally sufficient to observe bacterial cell shapes. A light microscope is also used to view results of gram stains. Gram staining is a technique used to determine whether certain bacteria can absorb the stain-causing bacterial cells to appear blue, i.e., gram positive, or red, i.e., gram negative. Gram stains and cell shapes are important diagnostic tools used to determine the species of unknown bacteria, particularly in cases of human bacterial infection.

Autoclaves Are for Sterilization

• Petri dishes, inoculating loops, media and any materials used to grow pure microbe cultures cannot be contaminated with other microbe species. The autoclave is used to sterilize equipment and media before it is used to grow microbes. It is also used to sterilize equipment and cultures after completing any experiment to prevent the spread of infectious materials. An autoclave is a large pressure cooker capable of temperatures exceeding 100 degrees Celsius. The increase pressures inside the autoclave allows water-based agars and nutrient broths to boil at temperatures greater than 100 degrees Celsius. It is a guaranteed method of sterilization.

Working in a Sterile Environment

• Transferring individual bacterial cells into a liquid media or agar plate requires a sterile environment to prevent contamination from surrounding air and bench surfaces. Microbiologists typically use a laminar airflow hood to create a sterile workbench. The laminar hood removes microbes by filtration from a constantly moving supply of air, which eliminates potential contaminating microbes on a work surface. Researchers can work with pure bacteria and fungal cultures without fear of contaminating the desired microbe cultures inside the laminar airflow hood.

Viewing Smallest Microbes with Electron Microscopy

• An electron microscope can be used to view small viral particles.

  Textbook pictures showing great detail for bacteria, fungal spores and particularly virus particles are performed using the electron microscope. The advantage of the electron microscope is that electrons are smaller than visible light particles and greatly increase potential resolution of the item being viewed. Light microscopes are limited to amplifying an object 1,000x without losing resolution. The electron microscope can amplify objects up 100,000x actual size. Researchers have produced magnificent photographs of virus particles using the electron microscope.