How To Identify Bacteria Under A Microscope | Step By Step Guide

Microscopes are great magnifying tools to ease your exploring curiosity. There are many of them available for loads of different purposes.

But you might be a biological microscope user as you are already here.

A compound microscope with a good magnification range is best for looking at and identifying microbes and bacteria.

But if you do not know how to identify bacteria under a microscope, then do not worry, as this article is going to help you out.

I will explain all that is necessary, so let’s get started!

Why is it Necessary?

A question arises why it is really necessary.

While working on microscopes and dealing with biological specimens, you should be aware of the fact that what kind of beings you can come across and how to look for them.

Bacteria is a very important microorganism. Its knowledge is useful in many fields related to biology. Thus, you should also know about it.

Type of Microscope Used

Before getting into the process, you should also know about the suitable microscopes for the job and also if your microscope is sufficient for that or not.

The most suitable microscope that you will find for this job is a compound microscope.

But keep in mind that only the magnification of 1000X-2500X will give the desired results.

Thus, light microscopes that are usually called compound microscopes, are best for this job.

Type of Bacteria We Usually Find

The main types that you can see with the aid of a microscope include these three mains; cocci, bacilli, and spiral.

Keep in mind that the microscope should also be capable enough. Usually, for that, you should assure maximum magnification, focus, and good illumination as well.

There are many other types of bacteria that need some other specifications in the optical instruments.

How to Find?

1. Culturing

Before getting into the viewing process of microorganisms like bacteria, you first have to grow them in a nutrition rich culture. Different bacteria require different nutrition supply.

The common types of nutrition culture media include nutrition agar media, selective agar, and differential culture media for the different types, respectively.

2. Slide Preparation

Here comes the second important part. This part comprises placing the bacteria layer over a glass plate that is usually termed as slide preparation.

The stuff required for this job includes a:

• Glass slide
• Burner
• Distilled water
• Bacteria sample
• And marker

Using your marker spot is where you are going to place the bacteria.

For smearing, place a small drop of water in that region.

You would need an inoculation loop as well. Place the inoculation loop over the burner to make it red hot and then let it cool.

Now using this loop, remove some bacteria colony from the media.

Now mix the bacteria in water and allow the slide to dry. The slide is prepared.

3. Staining

Sometimes bacteria seem translucent, and to view them, you have to stain them first. It helps to see the structural components of the microorganisms.

The most common staining materials include safranin, crystal violet, methylene blue.

You have to cover the slides under a staining agent for about 2 minutes to stain them. Once it is done, you can view the bacteria easily.

Identification

Now comes the most awaited step. If you are familiar with the types of bacteria, you will easily be able to identify them when viewing them under the microscope.

The physical characteristics of bacteria are important in this sense. The things to remember are the shape and size of the bacteria.

Once you are done with all the prerequisites, now you have to identify the bacteria based on its appearance.

The main types that I mentioned earlier as well are:

Cocci

These bacteria are usually of sphere shape and are the most common ones as well.

There are things to notice like diplococci are for pairs of cocci, streptococci refer to the chain, and staphylococci refer to clusters of cocci. Here cocci refer to the sphere.

Bacilli

These bacteria are rod-like in shape. Here there is diplobacilli for two bacilli while streptobacilli for chains of bacilli. Thus, you will be easily able to identify these bacteria when seen.

Spiral

This is the bacteria that comes in a very simple shape of a spiral. While classifying, you should know that spirillum refers to thick, while spirochetes refer to slender ones.

These were the identifications on the basis of shapes and size, but there is more than you can have an idea about.

Let’s classify them on the basis of gram-positive or gram-negative. But remember that staining is necessary for this type of identification.

Gram-Positive Bacteria

These bacteria impart a purple/bluish appearance on viewing. They have a thick layer of peptidoglycan to which the violet stain attracts.

This is the reason behind that purple-bluish appearance. This falls in the category of gram-positive bacteria, and thus you can identify the bacteria by these traits.

Gram-Negative Bacteria

On the contrary, these bacteria do not have that thick layer that I mentioned in the gram-positive section.

These bacteria, instead of violet agents, go with safranin to give a red appearance. For instance, cyanobacteria can be seen.

This technique of gram staining is very effective in the identification of bacteria. Thus, we have discussed some main aspects to identify the bacteria.

But keep in mind to follow proper precautions while performing the procedures not to get faulty results and also to stay from infections.

Conclusion

The microscope helps a lot in viewing bacteria and their behaviors. But the process of identifying them is quite long if you are a beginner.

Once you get used to it, you will find it pretty easy to work on. Also, I have tried to touch on all the important aspects.

But, learning starts from doing. You should confidently perform by hand to actually see the results.

Remember to realize the microscope compatibility, the types that can be seen of bacteria, and the step by step guide to come up with something good when performed.