Hanging drop method – Principal, Procedure and Observations

Introduction:

The hanging drop method is a widely used laboratory technique that has been used for many years in the field of microbiology. This technique is used to study the behavior of microorganisms in a controlled environment. It involves suspending a small drop of liquid containing microorganisms from a coverslip using a special apparatus. The technique is commonly used to observe the motility, morphology, and behavior of microorganisms.

In this blog post, we will discuss the principle of the hanging drop technique, the procedure involved in performing the technique, and the observations that can be made using this technique.

Principle of Hanging Drop Technique:

The principle of the hanging drop technique is based on the principle of surface tension. The surface tension of the liquid in the drop holds the drop in place on the coverslip. The drop is suspended upside down, and the microorganisms in the drop are free to move around the drop without being disturbed by their surroundings. This allows for the observation of their behavior in a controlled environment.

Procedure Involved in Performing the Hanging Drop Technique

The hanging drop technique involves the following steps:

1. Place a small drop of liquid containing the microorganisms on a coverslip.
2. Place a special apparatus on the coverslip. The apparatus is designed to hold the coverslip in place and suspend the drop of liquid upside down.
3. Observe the microorganisms in the drop under a microscope.

Observations Made Using the Hanging Drop Technique

The hanging drop technique is used to observe the motility, morphology, and behavior of microorganisms. Some of the observations that can be made using the hanging drop technique include:

1. Motility: The hanging drop technique allows for the observation of the movement of microorganisms. This can be used to study the motility of bacteria, flagellates, and other microorganisms.
2. Morphology: The hanging drop technique can be used to study the morphology of microorganisms. This allows for the observation of the size, shape, and structure of microorganisms.
3. Behavior: The hanging drop technique can be used to study the behavior of microorganisms. This allows for the observation of the response of microorganisms to their environment.

Advantages and Disadvantages of the Hanging Drop Technique

The hanging drop technique has several advantages and disadvantages. Some of the advantages of the hanging drop technique include:

1. Controlled environment: The hanging drop technique allows for the observation of microorganisms in a controlled environment.
2. High resolution: The hanging drop technique allows for the observation of microorganisms at a high resolution.
3. Easy to perform: The hanging drop technique is easy to perform and requires only a few pieces of equipment.

Some of the disadvantages of the hanging drop technique include:

1. Time-consuming: The hanging drop technique can be time-consuming, particularly if the microorganisms being observed are slow-moving.
2. Limited observation time: The hanging drop technique is limited in terms of the amount of time that can be spent observing microorganisms.
3. Limited sample size: The hanging drop technique is limited in terms of the amount of sample that can be observed.

How the hanging drop technique differs from other techniques used to study microorganisms?

Yes, the hanging drop technique is one of the many techniques used to study microorganisms, and it differs from other techniques in several ways.

1. Wet Mount Technique: In the wet mount technique, a small amount of the sample is placed on a microscope slide and covered with a cover slip. The sample is observed under a microscope, and any movement or changes in the sample can be observed. However, the wet mount technique does not allow for long-term observation, and the sample may dry out quickly.
2. Smear Technique: In the smear technique, a small amount of the sample is spread onto a microscope slide and allowed to dry. The sample is then stained, and the slide is observed under a microscope. While the smear technique allows for the observation of the morphology and structure of microorganisms, it does not allow for the observation of motility or behavior.
3. Agar Plate Technique: In the agar plate technique, a sample is inoculated onto the surface of a solid agar medium and allowed to grow. The colonies that form can be observed under a microscope. While the agar plate technique allows for the observation of the growth of microorganisms, it does not allow for the observation of individual microorganisms or their behavior.
4. Hanging Drop Technique: The hanging drop technique differs from the other techniques in that it allows for the observation of the motility, morphology, and behavior of microorganisms in a controlled environment. The hanging drop technique suspends a small drop of liquid containing microorganisms from a coverslip using a special apparatus. This allows for the microorganisms to move freely, making it easy to observe their behavior and motility.

Conclusion:

The hanging drop technique is a widely used laboratory technique that allows for the observation of the motility, morphology, and behavior of microorganisms in a controlled environment. While the technique has some disadvantages, its advantages make it a valuable tool for microbiologists. By understanding the principle of the hanging drop technique and following the proper procedure, researchers can make accurate observations about the behavior of microorganisms.

References:

https://bio.libretexts.org/

FAQS:

Q1. What is the hanging drop technique?

The hanging drop technique is a laboratory technique used to observe the behavior of microorganisms in a controlled environment. It involves suspending a small drop of liquid containing microorganisms from a coverslip using a special apparatus.

Q2. What is the principle behind the hanging drop technique?

Ans. The principle behind the hanging drop technique is based on the principle of surface tension. The surface tension of the liquid in the drop holds the drop in place on the coverslip, allowing for the observation of the behavior of microorganisms in a controlled environment.

Q3. What are the steps involved in performing the hanging drop technique?

Ans. The steps involved in performing the hanging drop technique include placing a small drop of liquid containing microorganisms on a coverslip, placing a special apparatus on the coverslip to hold the coverslip in place and suspend the drop of liquid upside down, and observing the microorganisms in the drop under a microscope.

Q4. What can be observed using the hanging drop technique?

Ans. The hanging drop technique can be used to observe the motility, morphology, and behavior of microorganisms.

Q5. What are the advantages of the hanging drop technique?

Ans. Some of the advantages of the hanging drop technique include a controlled environment for observation, high resolution for observation, and easy to perform with minimal equipment.

Q6. What are the disadvantages of the hanging drop technique?

Ans. Some of the disadvantages of the hanging drop technique include a time-consuming process, limited observation time, and limited sample size.

Q7. What types of microorganisms can be observed using the hanging drop technique?

Ans. Bacteria, flagellates, and other microorganisms can be observed using the hanging drop technique.

Q8. What is the difference between the hanging drop technique and the wet mount technique?

Ans. The hanging drop technique suspends the microorganisms in a drop of liquid, whereas the wet mount technique places the microorganisms directly on a slide with a drop of liquid.

Q9. What are some common applications of the hanging drop technique?

Ans. The hanging drop technique is commonly used in microbiology research to study the behavior of microorganisms, such as bacterial motility and biofilm formation.

Q10. Can the hanging drop technique be used for clinical diagnoses?

Ans. The hanging drop technique is not commonly used for clinical diagnoses as it is time-consuming and requires specialized equipment. However, it may be used in certain cases where the observation of microorganisms is necessary for diagnosis.

Q11. What is the use of hanging drop test?

Ans. The hanging drop test for stool is performed to visualize the motility or movement pattern of microorganisms in the stool sample and identify them from these patterns to help in the diagnosis of a disease caused by these microorganisms. The test principally helps in the diagnosis of Cholera.

Q12. What is the function of hanging drop slides in microbiology?

Ans. A hanging drop slide is a type of microscopic preparation used to observe motility of bacteria. It is a wet mount and a drop of the bacterial culture is placed on the coverslip.

Q13. Why is petroleum jelly used in the hanging drop technique?

Ans. The jelly holds the cover slip to the slide and also keeps the suspension from drying out.

Q14. what type of material needs during Hanging drop method?

• fresh cultures (broth medium less than 24 hours old is optimal) of various bacteria (assigned by instructor)
• depression slides
• cover slips
• petroleum jelly

Q15. What is hanging drop test for?

Ans. Hanging drop test is performed on the stool to measure the level of mobility of organism such as bacteria in the stool. Also known as Hanging Drop for Vibrio Cholerae Dark Illumination Stool test, it is performed to detect the Pseudomonas infection and to analyze the treatment of the infection.