Basic Laboratory Equipment Used in Microbiology | Biology

In the laboratory, eight main types of instruments are used:- 

1. Balance 

2. Centrifuge 

3. Hot Air Oven 

4. Incubators 

5. Water Bath 

6. Microscope

7. Autoclave 

8. Laminar Flow.

By advancement in technology to make the laboratory testings more accurate, fast, reliable and cost effective, we require these instruments with its proper care and maintenance.

Equipment # 1. Balance:

A balance is used to find out the mass of a substance by comparing it with known masses. These are used to weigh the chemicals accurately.

Physical balance is based on the principle of moments according to which, when a body is in equilibrium, under the action of a number of forces acting on it in the same plane, the sum of the clockwise moments is equal to the sum of the anticlockwise moments. For a physical balance with both arms of equal lengths, Weight on left pan = Weight of standard masses in right pan. Since weight is constant at the place, Mass of the object in left pan = Mass of standard weights in the right pan.

Care and Maintenance:

1. The balance should not be loaded with a weight greater than the maximum.

2. Clean the balance after use.

3. Never weight the substance by placing it directly on the pan.

Equipment # 2. Centrifuge:

They are designed to accurate the sedimentation process by using centrifugal force.

Centrifuge is applying centrifugal force to separate the useful component in mixtures of liquids and solids or liquids and liquids.

Centrifuge is mainly used to separate solids from liquids in suspension or separate two liquids with different density and non-homogenous liquids, for example, separate cream form milk, and also it can be used to remove liquids existed in solids, such as special speeding tubular centrifuges can separate the mixed gas content with different density, depending different density and particle size of solid particles in the liquid and different characteristics of the subsiding speed centrifuge, the sedimentation centrifuge also can classified solids according to different density and particle size.

Centrifuge is widely used in chemical, oil, food, pharmaceutical, beneficiation, coal, water treatment and shipping etc.

Centrifuge has a drum rotating its axle called bowl, generally derived by motor. Suspension or emulsion is introduced to the bowl and rotate with bowl with the same speed, eject separately under the centrifugal force. Usually, high separation speed, high separation ratio.

The principle of centrifuge is divided to centrifugal filtering and centrifugal sedimentation. Centrifugal filtering is made suspension become filtrate under the centrifugal force. And the centrifugal sedimentation is applied different density to separate suspension and emulsion and realize liquid-solid or liquid-liquid separation.

Care and Maintenance:

(1) Place the centrifuge on a firm base. Before the centrifugation the centrifuge tubes should be balanced properly.

(2) The chamber should be kept clean. All the spells should be cleaned immediately.

Equipment # 3. Hot Air Oven:

This kind of dry heat sterilization is recommended when it is undesirable that steam make contact with the material to be sterilized. This is true for certain glassware’s – Petri plates, Pipettes as well as for substances like oil, powder, etc. The apparatus employed is an electric/gas oven. Even the kitchen oven can be used. For laboratory glassware’s 1 hour exposure to a temperature at 160°C is enough for sterilization.

It is used mainly for dry sterilization for, drying glassware’s and some other metallic instruments.

Care and Maintenance:

1. Don’t forget to put off the main switch when the heating period is over.

2. Clean the hot air oven properly after use.

Equipment # 4. Incubators:

Principles of Operation:

Light bulbs heat air in the bottom part of the incubator. The air passes over a container with evaporating water, so that its humidity increases. The warm, humid air then flows upwards (chimney effect) into the compartment. A thermostat in an exit hole compares the air temperature with the desired temperature. If it is too high, the light bulbs will be switched off; if it is too low, the bulbs will be switched on.

The incubator operates with a thermostat that keeps the temperature of the air at a constant, adjustable value.

They are used for growing microorganisms on various culture media; it must be properly cleaned before and after uses.  

Equipment # 5. Water Bath:

It is used to carry out various chemical reactions at specific temperature. Depending upon the requirement of an experiment. It is often essential to keep a liquid mixture at an exact temperature without a gradient of heat (the bottom being hotter than the top) to make it “cook” properly. To do this scientists (and cooks) often submerge the vessel needing this controlled environment into a bath of water at a controlled temperature.

The advantage is that the water in the bath presents the heated material with a constant temperature that will not exceed 100°C (the boiling point of water) so that over heating or scorching is avoided. The laboratory water bath is slightly more complex than the kitchen version (the double boiler) as the temperature can be controlled through sensors to within a degree of the desired temperature.

Care and Maintenance:

(1) The water bath should be sufficiently fitted with water before use.

(2) Don’t forget to put off main switch after use.

(3) Cover the water bath when not in use. 

Equipment # 6. Microscope:

Microscope consists of two lens called eye lens and objective lens, objective lens is lens kept behind object and eye lens is keep on the top of microscope i.e. on the place through which we look, firstly the object is placed behind the objective of microscope which is turned into virtual, erect and magnified image, later this image is thought to be the object for the eye lens and this objects forms real, inverted and magnified image.

(a) A Microscope is used to study proper and enlarged and well defined images of object, too small to be observed with naked eyes.

(b) Wipe the objectives by using a soft cloth by moving the cloth across.

Oil – Immersion Objective:

1. Remove the oil with an absorbent paper.

2. Moisten the cloth with xylene and wipe the lens carefully cleaning the Eyepiece.

Cleaning the Eyepiece:

1. Clean the upper surface of the eyepiece with a soft cloth.

2. Clean the lower surface of the eyepiece with cloth and faint brush.

Cleaning the Condenser:

1. The condenser is cleaned with a soft cloth, moistened with xylene.

Cleaning the Support and the Stage:

1. Clean with a soft piece of cloth with xylene.

The stage can be cleaned thoroughly well by using a petroleum jelly.

Equipment # 7. Autoclave:

Autoclaving is one of the technique used in moist heat sterilization. The equipment used is called as Autoclave.

The principle behind the working of an Autoclave is the higher the pressure created inside the autoclave, the higher would be the attainable temperature inside it.

The boiling point of water at normal atmospheric pressure is 100°C.

When the free-flowing steam at a temperature of 100°C is subjected under pressure of 1 atmosphere above the sea-level pressure i.e. 15 pounds pressure per square inch, the temperature inside the autoclave happens to rise up to 121°C, which is an usual and common parameters employed in the moist heat sterilization.

Principle involved in Autoclave is moist heat sterilization. It causes coagulation of cell proteins at a temperature lower than hot air oven. At the point of condensation steam liberates thermal energy equal to its heat of vaporization. So autoclaving is mostly done at this temperature for a period of 15-20 minutes under 15 lb pressure. As the temperature increases, steam gets energized increasing its penetration capability.  

Care and Maintenance of Autoclave:

(i) Disconnect the autoclave from the main power supply before cleaning.

(ii) Ensure that no material falls into the base chamber i.e. autoclave tape, glass, etc. as they may affect the operation of the exhaust valves.

(iii) Ensure that the pressure gauge is operating correctly.

(iv) Heat the autoclave on a secure burner.

(v) Clean and dry the unit after the day use.

(vi) Use autoclave only for its intended purpose.

(vii) Weekly clean both interior and exterior with warm, soapy water ensuring the electrical parts are kept dry (In case of electric autoclave).

Warning:

(i) Do not operate the autoclave without water. Avoid Using Hard Water in the unit.

(ii) Make sure the rubber seal is in a good Shape and condition.

(iii) Do not put any extra weight on the stopcock.

(iv) Close the Autoclave lid properly and never try to open it by force without first releasing the steam.

(v) Do not use any alkaline solution in the unit.

(vi) Clean and Dry the unit after a day uses.

Equipment # 8. Laminar Flow:

Laminar flow hoods are essential machines to medical research. They are an enclosed worktop that scientists can keep entirely sterile. In the hoods, scientists can do various treatments on cells or experimental animals, keeping both the test subjects safe from outside contaminants, and scientists safe from possible threats inside the hood, like virus particles. However, they require strict maintenance to ensure the region inside the hood remains sterile and safe.

In a laminar flow hood the air is passed through a HEPA (High Efficiency Particulates Air) filter which removes all airborne contamination to maintain sterile conditions.

A laminar flow hood consists of a filter pad, a fan and a HEPA (High Efficiency Particulates Air) filter. The fan sucks the air through the filter pad where dust is trapped. After that the pre-filtered air has to pass the HEPA filter where contaminating fungi, bacteria, dust etc. are removed. Now the sterile air flows into the working area where you can do all your flasking work without risk of contamination.  

Important parameters to make sure that the hood works efficiently:

(i) The HEPA filter has to remove all airborne materials.

(ii) The air speed in the working area has to be about 0.5 m/s.

The Two Types of Laminar Flow Hoods:

Before you start building your flow hood you have to decide if you prefer a vertical or horizontal air flow in the flasking area. In a vertical flow the air moves from the top of the working area to the bottom and leaves the flasking area through holes in the base. When you use a flow hood with horizontal air flow the air moves from the back of the working area to the front.  

Filters:

Laminar flow hoods are equipped with filters that trap particles that might flow into the hood and contaminate the air in the sterile environment. These filters, ranging from basic air filters to the more complex high efficiency particulate air, or HEPA, filters, must be changed on a regular basis to ensure they are effective. Each type of filter has a different lifespan. For example, HEPA filters can last from 3 to 5 years. Filters should be marked so that you know when to change them.

Blower:

Most of the front of the flow hood is protected by a sliding glass door that lifts to allow a scientist to reach in his or her hands. When the window is lifted up, a blower begins to push air out, creating a barrier that stops environmental air from getting into the sterile hood.

The blower is an essential part of the flow hood’s effectiveness. Regular check-ups to ensure that is blowing at a steady, strong rate are necessary. Most research institutions have a scheduled cycle for flow hood blower maintenance in order to keep them in working order.

Surfaces:

Each time a researcher uses the hood, they need to make sure the surfaces within it are cleaned. Strong acids and bases can eat away at the metal or acrylic that covers the worktop and walls, and must be cleaned immediately. To keep the area free of bacteria or other foreign contaminants, cleaning with a fast-evaporating alcohol, such as an ethanol mixture, is the best way to keep the surfaces sterile.

.