# A lecture on Identification of instruments used in biofertilizer laboratory with principle and use

Ajeet Kumar

► To cite this version:

Ajeet Kumar. A lecture on Identification of instruments used in biofertilizer laboratory with principle and use. Master. Biopesticide and Biofertilizer (Elective course), Dr. Rajendra Prasad Central Agricultural University, Samastipur, India. 2025, pp.1-14. [hal-05267014](https://hal.science/hal-05267014v1)

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Submitted on 18 Sep 2025

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Distributed under a Creative Commons Attribution 4.0 International License
Dr. Rajendra Prasad Central Agricultural University
Pusa (Samastipur) - 848125, Bihar

A Lecture notes

On

Identification of instruments used in biofertilizer
laboratory with principle and uses

<figure><img src="image_2.png" /></figure>

COURSE TITLE: Biopesticide and Biofertilizer

(Elective course*)

COURSE NO.: ASS-307

CREDIT HOUR: 3 (2+1)

Dr. AJEET KUMAR

Assistant Professor-cum-Scientist (Soil Science)

Department of Microbiology

Collage of Basic Sciences and Humanities, Dr. RPCAU, Pusa

2025
# Instruments Used In Microbiology Lab with Principle and Uses

Dr. AJEET KUMAR<fnref n="1" />

## List of Instruments used in Microbiology Lab

1. Analytical Balance

2. Autoclave

3. Bunsen burner

4. Centrifuge

5. Colony Counter

6. Deep Freezer

7. Homogenizer

8. Hot plate

9. Hot air oven

10. Incubator

11. Laminar Air Flow/ Laminar Hood

12. Magnetic Stirrer

13. Microscope

14. pH Meter

15. Spectrophotometer

16. Vortex Mixture/ Vortexer

17. Water Bath

18. Water Distiller

19. Culture tube

20. Test tube

21. Inoculation needle/rod/loop

22. Laboratory Heat Sealer

23. Vacuum pump

24. Microwave ovens

25. Lab incubators

26. Sand bath

27. Oil bath

28. Fermentor

<footnote n="1">¹Assistant Professor-cum-Scientist (Soil Science-Soil Microbiology, Soil fertility, Soil Chemistry), Department of Microbiology, College of Basic Sciences & Humanities (CBS&H), RPCAU, Pusa-848125, Bihar. E-mail: ajeet.sri@rpcau.ac.in</footnote>
# 1. Analytical Balance

An analytical balance is a type of balance that is commonly used for the measurement of mass in the sub-milligram range.

## Working Principle

<figure><img src="image_3.png" /></figure>

These types of balances are made with a measuring pan enclosed in a transparent covering that prevents small particles or air currents from getting collected on the pan.

<figure><img src="image_4.png" /></figure>

An electric analytical balance uses the force necessary to counteract the mass rather than measuring the mass itself.

<figure><img src="image_5.png" /></figure>

An electromagnet is used to create a force required to achieve a balance with the mass of the substance and the resulting force is displayed.

## Uses

* As they are highly precise and based on advanced technology, analytical balances are explicitly used in laboratories for the effective completion of tasks like weighing test materials and sampling amounts, formulation, density determination, purity analysis, quality control testing, and material and conformance testing

# 2. Autoclave

An autoclave is a pressurized chamber used for the process of sterilization and disinfection by combining three factors: time, pressure, and steam

## Working Principle

<figure><img src="image_6.png" /></figure>

Autoclaves use steam as their sterilization agent. The basic principle of an autoclave is that all the items within the autoclave come in direct contact with the steam for a particular period irrespective of the nature of the material- whether it is liquid, plastic ware, or glassware.

<figure><img src="image_7.png" /></figure>

The amount of time and the temperature depends on the type of material being sterilized and the increase in temperature of the cycle allows for shorter periods.

## Uses

* Autoclaves are mostly used for the sterilization of medical or laboratory equipment with the capacity of sterilizing a large number of materials at once.

* They are commonly used for the preparation of culture media during laboratory applications.

<figure><img src="image_8.png" /></figure>
## 3. Bunsen burner

Bunsen burner is a standard tool used in laboratories, named after Robert Bunsen. It is a gas-fueled single open flame.

### Working Principle

<figure><img src="image_9.png" /></figure>

This burner is made with a metal tube on a flat base with a gas inlet at the bottom of the tube, which may have an adjustable valve. On the sides of the tube are openings that can be adjusted with a collar to control the amount of air that can enter.

<figure><img src="image_10.png" /></figure>

Once the burner is connected to a gas source, the gas is forced by the gas pressure so that the gas reaches the top where the flame is ignited with a match or a lighter.

### Uses

* It is commonly used for processes like sterilization, combustion, and heating. In medical or microbiology laboratories, it is commonly used for micro-loop sterilization.

## 4. Centrifuge

A centrifuge is a device that allows the rotation of an object about a single axis, where an outward force is applied perpendicularly to the axis. A laboratory centrifuge is motor-based and allows the rotation of a liquid sample resulting in the separation of the components of the mixture.

### Working Principle

<figure><img src="image_11.png" /></figure>

A centrifuge works on the principle of sedimentation, where the high speed of the rotation causes the denser particles to move away from the center while smaller, less dense particles are forced towards the center.

<figure><img src="image_12.png" /></figure>

Thus, the denser particles settle at the bottom while the lighter particles are collected at the top.

<figure><img src="image_13.png" /></figure>

In a laboratory tabletop centrifuge, the sample tubes are aligned at an angle so that the particles have to travel a shorter distance before they hit the bottom.

### Uses

* The primary application of a centrifuge is the separation of particles suspended in a suspension. It can be used for the separation of cell organelles, nucleic acid, blood components, and separation of isotopes.

## 5. Colony Counter

A colony counter is used to estimate the density of a liquid culture by counting the number of CFU (colony forming units) on an agar or culture plates. It is used for counting microorganism which is not visible by naked eye. The magnifying glass (convex lense) is fitted in this equipment.

### Working Principle

<figure><img src="image_14.png" /></figure>

This instrument can accommodate different sizes of plates which are scanned on top with UV, white light and/or fluorescent illumination.
<figure><img src="image_15.png" /></figure>

One can accomplish the counting either manually with the touch pressure or with a digital
counter.

Uses

o A colony counter is primarily used for counting the number of colonies present on a culture plate to estimate the concentration of microorganisms in liquid culture.

6. Deep Freezer

Working Principle

<figure><img src="image_16.png" /></figure>

Deep freezers are based on the principle that under extremely low temperatures, there is
minimum microbial growth which allows for the protection and preservation.

<figure><img src="image_17.png" /></figure>

Based on this principle, we can even preserve cultures over a long period of time without
any change in the concentration of the microorganisms.

Uses

o A deep freeze can be used for the preservation of different things used in the laboratories for a very long period of time. Deep freezers are used in laboratories to store and preserve isolated microbes for a more extended period of time.

7. Homogenizer

Homogenizer is a device used in laboratories for the mixing of various liquids and materials like tissue, plant, food, soil, and many others.

Working Principle

<figure><img src="image_18.png" /></figure>

This instrument is based on the principle that when large globules in coarse emulsion are passed under high pressure through a narrow orifice, they break down into smaller particles giving a more uniform and stable mixture.

<figure><img src="image_19.png" /></figure>

A homogenizer has a metal rod with narrow parallel openings in the form of a comb at the end which acts as the orifice for the homogenization process.

Uses

o A homogenizer is primarily used to disrupt cells to acquire cell organelles for different microbiological processes.

o It is used in the preparation step before the extraction and purification of different macromolecules like proteins, nucleic acids, and lipids.

8. Hot plate

A hot plate is a stand-alone appliance used in microbiology laboratories as a table-top heating system.

Working Principle

<figure><img src="image_20.png" /></figure>

Unlike the traditional ways of producing heat through fire, a hot plate produces heat by the flow of electricity.

<figure><img src="image_21.png" /></figure>

On a hot plate, electricity runs through the coils which have a high level of electrical resistance. The resistance in the coils converts the electrical energy into heat energy which causes the coils to release heat.
## Uses

* In a laboratory, hot plates are used to heat glassware and its components.

* They are used over water baths as water baths might be hazardous in case of any spills or overheating.

# 9. Hot air oven

A hot air oven is an electrical device that is used for sterilization of equipment, dried glassware or samples using dry heat.

## Working Principle

<figure><img src="image_22.png" /></figure>

A hot air oven is a type of dry heat sterilization which is performed on dry materials and on substances that do not melt or catch fire under high temperatures.

<figure><img src="image_23.png" /></figure>

There are **two types of hot air ovens** based on the working principle

<figure><img src="image_24.png" /></figure>

**Forced air hot air oven:** In this type of hot air oven, the heated air inside the oven is distributed throughout the oven with a fan. This prevents the rising of hot air towards the top while keeping the cold air at the bottom. This allows for the adequate heating of materials inside the oven.

<figure><img src="image_25.png" /></figure>

**Static air hot air oven:** In this type of oven, the heat is produced by coils present at the bottom of the oven with no fan. The hot air rises and doesn't allow the effective sterilization of the materials.

<figure><img src="image_26.png" /></figure>

The equipment inside the oven acquires heat and passes the heat towards the center, one layer at a time which allows for effective dry heat sterilization.

## Uses

* A hot air oven can be used to sterilize materials like glassware, metal equipment, powders, etc.

* It allows for the destruction of microorganisms as well as bacterial spores.

<figure><img src="image_27.png" /></figure>
## 10. Incubator

An incubator is a device used in laboratories for the growth and maintenance of microorganisms and cultures. Incubator provides an optimal temperature, pressure, moisture, among other things required for the growth of microorganisms.

### Working Principle

- The incubator is based on the principle of maintaining a proper atmosphere for the growth of microorganisms.

- Incubators have a heating system that allows for the temperature within the incubator to be adjusted according to the type of organism allowed to grow inside.

- Similarly, they are provided with adjustments for maintaining the concentration of CO₂ to balance the pH and humidity required for the growth of the organisms.

- Variation of the incubator like a **shaking incubator**, which allows for the continuous movement of the culture required for cell aeration and solubility studies.

### Uses

- Incubators have a wide range of applications including cell culture, pharmaceutical studies, hematological studies, and biochemical studies.

- Incubators can also be used in the steam cell research area.

## 11. Laminar Air Flow/ Laminar Hood

Laminar Hood is a closed device primarily for processes or instruments sensitive to microbial contamination.

### Working Principle

- A Laminar Hood is made up of stainless steel, avoiding joints and corners to prevent the accumulation of bacterial spores.

- This device creates a sterile environment with the flow of sterile air through a **High-Efficiency Particulate Air (HEPA) filter** and shortwave **ultraviolet germicidal lamp** that sterilizes the workstation.

- Laminar Air Flow has to **turn on 15 minutes before to ensure complete sterilization** and the workstation should be **cleaned with ethanol** before and after use.

### Uses

- Laminar Hood is used to conduct processes that are sensitive to contamination.

- It is used for experiments related to isolation of microorganism, plant tissue culture and for the experiments of genetic transformation.

<figure><img src="image_28.png" /></figure>

<figure><img src="image_29.png" /></figure>
## 12. Magnetic Stirrer/culture tube stirrer

Magnetic Stirrer is a device used in microbiology laboratories for the purpose of mixing the liquids/ or the material which is present in culture tube.

### Working Principle

<figure><img src="image_30.png" /></figure>

This device consists of a rotating magnetic or an electromagnet creating a rotating magnetic field that allows the stir bar (a piece of heavy metal) to move around in the vessel.

<figure><img src="image_31.png" /></figure>

It is coupled with a heating system to heat the liquid while it is mixed.

### Uses

* It is usually used for mixing various liquid components in a mixture in a chemical or microbiology laboratory.

* This device is used in place of other stirrers as it is noise-free and because the size of the stir bar is so tiny, there is less chance of contamination.

<figure><img src="image_32.png" /></figure>

## 13. Microscope

Microscopes are devices that allow the observer to have an exceedingly close view of minute particles.

### Working Principle

<figure><img src="image_33.png" /></figure>

There are different types of microscopes, each of which works on its respective principles. However, there is some commonality in them.

<figure><img src="image_34.png" /></figure>

The basic principle in a microscope is magnification. Based on the relative position of the object from the lens or electromagnets, different positions, nature, and magnification of the image can be achieved.

<figure><img src="image_35.png" /></figure>

Different types of microscopes are developed to cater to the specific needs of the observation. However, the common theme is magnification.

### Uses

* Based on the type of microscopes, different microscopes are used for different purposes.

* They are primarily used for the observation of minute particles which cannot be observed with naked eyes.
## 14. pH Meter

A pH meter is a device used in laboratories that measure the H-ion concentration in water-based solutions to determine the acidity or alkalinity of the solution. A **pH meter** is **often termed a "potentiometric pH meter"** as it **measures the difference** in electric potential between the **reference** and a **pH electrode**.

### Working Principle

- In a potentiometric pH meter, single or multiple glass electrodes, connected to a bulb selective to hydrogen ions, are attached to a metal rod.

- When the bulb with the electrodes is dipped into a solution, hydrogen ions in the solution exchange with positive charges on the electrode generating an electrochemical potential which is displayed in terms of pH units on display.

### Uses

- A pH meter is primarily used to measure the acidity of microbial cultures, soil, and water treatment plant.

- It can be used to measure the acidity level in wine and cheese during their production.

## 15. Spectrophotometer

The spectrophotometer is an optical instrument for measuring the intensity of light in relation to wavelength. Based on the amount of light absorbed by a coloured solution, a quantitative analysis of the solution can be done.

### Working Principle

- Spectrophotometry is based on the Beer-Lambert Law, which states the absorbance of light by a solution (of a particular wavelength) is directly proportional to the concentration of the substance.

- Different wavelengths of light are passed through a solution as different substances have better absorbance at different wavelengths. Based on the absorbance of a particular wavelength, the quantitative analysis of a solution can be done.

### Uses

- In a microbiology laboratory, a spectrophotometer is applied for the measurement of the substance concentration of protein, nucleic acids, bacterial growth, and enzymatic reactions.

## 16. Vortex Mixture/ Vortexer

A vortex mixture is one of the basic technologies used for the **mixing of samples in glass tubes or flasks** in laboratories.

### Working Principle

- It is based on the simple principle of causing reactions and homogenization by agitating the mixture.

- Motorized draft shafts present on the mixer oscillate and transfer the movement to the sample tubes causing the sample fluids to undergo turbulent flow.
## Uses

* Vortex mixer is mostly used for the mixing of various sample fluids in the sample tubes and also allows for the homogenization of cells and cell organelles.

## 17. Water Bath

Water Bath is a conventional device that is used for chemical reactions that required a controlled environment at a constant temperature.

### Working Principle

<figure><img src="image_36.png" /></figure>

A sensor in the device transfers water temperature to a reference value which is then amplified and a control system generates a signal for the heating system which heats the water to the desired temperature.

## Uses

* Water baths are primarily used for heating samples under a controlled temperature.

* These are suitable for heating chemicals that might be flammable under direct ignition.

<figure><img src="image_37.png" /></figure>

## 18. Water Distiller

A water distiller is a device that purifies water by the process of distillation. This is commonly used in, microbiology laboratories, organic chemistry laboratories and medical laboratories.

### Working Principle

<figure><img src="image_38.png" /></figure>

A water distiller is based on the principle of distillation.

<figure><img src="image_39.png" /></figure>

According to this process, water is first brought to a boil and then condensed into liquid form to obtain pure distilled water.

## Uses

* It is used to obtain distilled water required for lab tests as well as for the preparation of culture media.

## 19. Culture Tube

Culture tubes are often used in microbiology lab for handling and culturing all kinds of live organisms, such as molds, bacteria, seedlings, plant cuttings, etc. It is also used to store samples and other fluids. Mouth of tube is plain cut because rounded mouth causes problems in removing cotton plug of tube.
<figure><img src="image_40.png" /></figure>

**20. Test Tube**

Test tubes are widely used by chemists to handle chemicals, especially for qualitative experiments and assays. Their spherical bottom reduces mass loss when pouring, make them easier to wash out, and allow convenient monitoring of the contents.

<figure><img src="image_41.png" /></figure>

**21. Inoculation needle/rod/loop**

An inoculation needle is equipment used in the lab of microbiology. It is used in the transfer of microbial organisms from plate culture to needle by first sterilizing the needle to prevent contaminations. Inoculation needle is made up of **Nichrome alloy** {Nickel, Chromium, Manganese & Fe} which is heat resistant.

An inoculation loop, also known as a **smear loop** is a simple tool, primarily used by microbiologists **to take and transfer inoculum of a microorganism culture**.

**22. Laboratory Heat Sealer**

This instrument is used to seal the **pouches, plastic bags, sachets** that are used in packaging of biofertilizer. The apparatus is used to ensure the intactness or band of the plastic bags and other packaging bags that are used to pack different consumable as well as non-consumable goods.

**23. Vacuum pump**

Vacuum pumps are mechanical devices that enable the removal of air and gas molecules from a sealed area to create an area devoid of air or gas, their purpose is to clean and seal. Vacuum pumps come in wet or dry variants depending on the media being pumped through them.

**24. Microwave ovens**

Microwave ovens are used for **heating and defrosting in laboratories**. Improper use of a microwave can pose a number of hazards including: Ignition of flammable vapors. Electrical shock from ungrounded or faulty units. Microwave ovens used in laboratories for the rapid heating of material-either to dry them completely or to subject a work piece to
sudden thermal stress or electric field stress. **Determinations of the moisture content in soil or leaf tissue samples**, for example, can be made **within tens of seconds** rather than hours. It is often assumed that placing a load within a microwave oven will result in it being heated evenly as well as quickly.

**25. BOD incubators**

BOD (Biological Oxygen Demand) incubators are essential equipment in the laboratory that provides a temperature-controlled environment to support growth of microbiological cultures. **Here the materials kept in desired temperature for desired period of time.**

**26. Sand bath**

A sand bath is a common laboratory equipment made from a container filled with heated sand. It is used **to provide even heating for another container during a chemical reaction.**

<figure><img src="image_42.png" /></figure>

**27. Oil bath**

An oil bath is a type of heated bath used in a laboratory, most commonly used **to heat up chemical reactions**. It's essentially a container of oil that is heated by a hot plate or (in rare cases) a Bunsen burner. It is used in laboratories for reactions that require heating temperatures up to **200 degrees Celsius**. Oil baths provide uniform heat compared to other heaters. An oil bath is **a heating device which uses boiling oil as the temperature regulator**. Since different oils have different boiling points, it is possible to obtain a temperature near to the desired temperature by selecting oil with a boiling point as close as possible to the desired temperature.

<figure><img src="image_43.png" /></figure>
## 28. Fermenter

A fermenter is the equipment, which provides the proper environment for the growth of a desired organism. It is generally a large vessel in which, the organism may be kept at the required temperature, pH, dissolved oxygen concentration and substrate concentration. Different models of fermenters are available depending upon the necessity. A simple version model contains steam generator, sterilization process devices and agitator. A sophisticated fermenter contains pH regulator, oxygen level regulator, anti-foam device, temperature controller, etc.

<figure><img src="image_44.png" /></figure>

### True or False type questions:

1. **True or False:** An analytical balance measures mass by counteracting the mass with an electromagnet.

o **Answer:** True

2. **True or False:** Autoclaves use dry heat to sterilize equipment in laboratories.

o **Answer:** False (They use steam for sterilization)

3. **True or False:** A centrifuge works on the principle of sedimentation.

o **Answer:** True

4. **True or False:** A deep freezer is used to sterilize laboratory equipment.

o **Answer:** False (It is used to preserve samples by maintaining extremely low temperatures)

5. **True or False:** A homogenizer is used to heat glassware in microbiology laboratories.

o **Answer:** False (It is used to mix and homogenize materials)

6. **True or False:** A Bunsen burner is commonly used for micro-loop sterilization in microbiology laboratories.

o **Answer:** True

7. **True or False:** A hot air oven uses moist heat to sterilize equipment.

o **Answer:** False (It uses dry heat for sterilization)
8. **True or False:** The principle of a spectrophotometer is based on the Beer-Lambert Law.

o **Answer:** True

9. **True or False:** Laminar Air Flow provides a sterile environment using a HEPA filter.

o **Answer:** True

10. **True or False:** A pH meter measures the temperature of a solution.

o **Answer:** False (It measures the hydrogen-ion concentration or pH of a solution)