Is it possible to see bacteria

As the bacterial population increases in number, the colonies get larger and begin to take on a shape or form. These can be quite distinctive and provide a good way to tell colonies apart when they are similar in color or texture.

The following three characteristics can be described for bacteria when a single, separate colony can be observed. It may be helpful to use a magnifying tool, such as a colony counter or dissecting microscope, to enable a close-up view of the colonies.

Colonies should be described as to their overall size, their shape or form, what a close-up of the edges of the colony looks like edge or margin of the colony , and how the colony appears when you observe it from the side elevation.

Figure 4 shows a close-up of colonies growing on the surface of an agar plate. In this example, the differences between the two bacteria are obvious, because each has a distinctive colonial morphology. Using microbiology terms, describe fully the colonial morphology of the two colonies shown above. A full description will include texture, transparency, color, and form size, overall shape, margin, and elevation.

A culture medium must contain adequate nutrients to support bacterial growth. Minimally, this would include organic compounds that can provide the building blocks necessary for cellular reproduction. In many cases, predigested protein, such as hydrolyzed soy protein, serves this purpose and will support the growth of many different bacteria. These media formulations are generally referred to as complex media , to indicate that it is a mixture with many components.

Many media contain additional substances such as an antibiotic that may be selective for a particular type of bacteria by inhibiting most or all other types. Differential media will have additional compounds that permit us to distinguish among bacterial types based on differences in growth patterns. We will eventually use selective and differential media in our experiments, but the focus of this lab is to learn the basic culturing techniques, and therefore, the media used will be Tryptic Soy medium, a complex medium formulated with hydrolyzed soy protein.

The media you use in this lab and in all of the future labs will have already been prepared, but it is important for you as a budding microbiologist to understand and appreciate how culture media is prepared. With this in mind, your instructor may have you watch a brief video that demonstrates the art of media making. Pre-sterilized glass or plastic graduated pipettes Figure 5 are used to transfer specific volumes of sterile liquids accurately. It is important that you learn how to use these tools correctly, since it may be necessary to transfer sterile and sometimes contaminated liquids among various bottles and tubes.

Their appropriate use will be discussed and demonstrated in lab. Some tips to remember:. A portion of a 10 mL graduated pipette is shown in Figure 6. What is the volume of liquid in this pipette? Solid and semi-solid media.

Growing cultures of bacteria on solid media agar plate or slant permits us to view and identify colonial characteristics, and also provides a way to separate bacteria in a mixed culture. Bacteria may be grown in agar slant or stab media in tubes if the purpose is to maintain them in a longer term culture. Generally, bacteria grown on slants will remain viable for a few weeks to a few months, and sometimes longer if stored in a refrigerator.

In this laboratory, you will be introduced to aseptic techniques and basic lab skills needed to grow and maintain bacteria in culture. You will be applying these skills often, so mastery is important. Below, write the names of the two bacteria in the mixed culture and the appropriate BSL, as specified by your instructor:. The techniques needed will first be demonstrated by your instructor. Using aseptic technique, use a 10 ml graduated pipette to transfer 2 ml of broth to each tube.

As demonstrated, use a flame-sterilized inoculating loop to pick up from the surface of the M. Note how the broths look immediately after you inoculate them they should still look mostly clear.

Bacterial growth in broths is indicated by the development of a cloudy appearance. If the newly inoculated broth looks cloudy at the start, you will have no way to determine if this is due to bacterial growth during the incubation period.

If your broth looks cloudy, discard it and make another broth using less bacteria. Place the broth subcultures in an incubator at the temperature and time specified by your instructor. Separation of a mixed culture into individual colonies that can be subcultured to make pure cultures depends on how well the streak plate is prepared. The goal of streak plate method is to dilute the cells by spreading them out over the surface of the agar. This is accomplished in stages, as will be demonstrated in lab before you try it yourself.

Use the simulated agar surface below to practice the streak pattern using a pen or pencil. Also write M. As demonstrated, use a sterilized inoculating loop to pick up one M. Spread the bacteria over approximately a quarter of the plate, edge to edge. Consider this step 1. Flame the loop and cool it in the agar. Overlap the step 1 streak times to pull out a reduced number of bacteria, and spread them out down the side of the plate.

Consider this step 2. Overlap the step 2 streak times and spread over the surface. Continue this process, flaming the loop in between each step, until the entire surface of the agar plate is covered. After performing this with the M. Place the streak plate subcultures in an incubator at the temperature and time specified by your instructor. Obtain one slant tube containing TSA, and label it using a small piece of tape with your name and culture name M.

Using a sterilized inoculating loop , pick up a bacterial colony or piece of a colony from the surface of the plate culture of M. Place the slant subculture in an incubator at the temperature and time specified by your instructor. Obtain one stab tube containing semisolid TSA, and label it using a small piece of tape with your name and culture name E. Bacterias are called Microscopic organisms.

It has wide variety of shapes ranging from round to filament. Points: 1. No we cannot see the bacteria with naked eye. We can see with a microscope. Posted By: [Anonymous]. Even though bacterias are microscopic organism which means not able to see through naked eyes , there are 2 which can be seen through naked eye. They are - Thiomargarita Namibiensis - Epulopiscium Fishelsone. Points: 2. Javascript seems to be disabled in your browser. You must have JavaScript enabled in your browser to utilize the functionality of this website.

Bacteria are tiny living microorganisms that live in enormous numbers in almost every environment on Earth. From deep within the soil to inside the digestive tract of humans. In order to see bacteria, you will need to view them under the magnification of a microscopes as bacteria are too small to be observed by the naked eye. Most bacteria are 0. Bacteria have colour only when they are present in a colony, single bacteria are transparent in appearance.

It takes a skilled person to be able to differentiate bacteria from small dust and dirt which may be present on the slide.