Bacteria can be found in almost every bit of the universe; from soil to rocks to oceans. It is a well-known fact that bacteria reside on plants, on the surfaces of the human body, and also in the body. Do you want to see it? Don’t worry, here’s a complete guide that helps you finding bacteria under a microscope.
Generally, there’s the impression that bacteria are always destructive organisms; being food spoilers, a great hazard to agriculture, and infectious agents that victimize animals and humans. This is not always true; amazingly there are quite a few bacterial species carrying out destructive roles. Most are very useful organisms; bacterial cells are ten times greater than the human cells that exist in the human body.
There are a large number of bacteria that line the digestive system in humans and form the normal flora. If this naturally residing bacterial lining is damaged via some antibiotic intake during the treatment of certain diseases, then it also creates obstacles in living a healthy life till the damages are cured.
Therefore, multivitamins are always recommended to take along with the antibiotics to preserve the normal bacterial flora.
Mostly bacteria are not disease-causing pathogens; they serve with useful purposes of food processing and also recycle the soil nutrients if they are living in the soil and dead plant matter.
Structure of Bacteria
Learning about the basic structure of a simple bacterium is least perplexed. Its intra-cellular structures are few and convenient to understand. Each bacterium is a single-celled organism with an absent nucleus and no organelles found in its membrane. All the chromatin material is present on a single strand of DNA, which reveals all the genetic detailing of this tiny cell, not visible to the naked eye. Few species are a step ahead of the others in combating their killing agents that is the antibiotic. These comprise a special circular DHA, the plasmid, which has a gene for enhanced resistance or you can say more protection for this bacterium.
- Cocci (circular)
- Bacilli (rods)
- Vibrio (comma-shaped)
- Corkscrew shaped
Now the query is how can we observe these versatile organisms, and its definite answer is that we can do it via microscopes.
Process of Visualizing Bacteria in a Microscope
Step 1: Culture
Bacteria prevail naturally as single cells, clusters, pairs, or bunches, or long chains. If you choose a certain type of bacteria as your specimen, first you have to grow it in a bigger population in an appropriate culture medium.
Types of Culture Mediums
Nutrient Agar Media: It is the most widely used non-specific medium in which a huge variety of bacterial samples are cultured. They include all aerobic and non-aerobic bacterial organisms. On the basis of oxygen consumption, bacteria are divided on a wide scale.
Selective Agar Media: Mannitol salt is used as the basic constituent of this medium. It enables the multiplication of certain bacterial species while halting the growth process of all other bacteria introduced in Selective Agar.
Differential Media: In this medium, different materials are used to identify different bacteria and cultures the one that is required. For example, if you are looking to isolate and cultivate a Streptococcus colony, then introducing a Blood Agar Media would be the most appropriate. Streptococci have hemolytic properties and would become prominent if provided such a medium.
Step 2: Prepare a Neat Slide
Once the bacterial incubation period is achieved, it is time to prepare a bacterial smear on a glass slide. Once an accurate smear is ready, your slide can be viewed under a microscope to unveil the mysteries of bacteria.
How to Prepare Bacterial Slide – Step by Step Guide
First, you need a marker to mark a certain point on your slide where you will place your bacterial smear.
Secondly, with the help of an inoculation loop, introduce very little water at the spot of smear preparation.
At the Third step, heat the inoculation loop in the blue flame of the Bunsen burner, and let it glow red hot. Now allow the loop to cool down; immediately lift some bacteria from the culture broth with aid of this loop.
Thereafter, mix the bacteria with the water drop on the slide, carefully with the inoculation loop’s end while placing the bacteria.
Lastly, allow this mixture to dry at atmospheric air pressure/room temperature.
Step 3: Time to Stain your Slide
Staining is a crucial step for observation of your bacterial specimen. It will enable you to visualize the bacterial structures like cell wall, membrane, cytoplasm, and plasmid. Educational institutes and laboratory setups mostly use Methylene blue, Safranin, and Crystal Violet stains for this purpose.
To stain your slides,
First, organize them on a staining rack. Introduce the required stain with a dropper, over your bacterial smear, and allow it to dry for one to two minutes.
Next, wash away the excessive staining pigment bypassing your slide gently through the slow stream of water, then rinse your slide slightly.
Your slide is now ready to be viewed under a microscope.
Adjust it on the stage of your microscope, and make necessary adjustments for a clear view of your specimen’s structures depending upon the focus modifications that your microscope possesses.
Most important of all is, the entire process of visualization of bacteria under a microscope must be conducted with high sterilization practices.
More to Know
The staining technique is also a helpful method for the basic division of the bacteria on the basis of peptidoglycan in their structure. All Gram-positive bacteria stain blue or purple as they retain the complex of crystal violet-iodine stain. Gram-negative bacteria stain red as the Safranin stain stays in their structure.
Phase Contrast Compound Microscope is the best suitable to visualize bacterial structures accurately. It minimizes all detailed interpretation errors by producing a high-field contrasting view of the intracellular structures of these transparent organisms.