Archive for the ‘Laminar Air Flow’ category

Laminar Air Flow and Plant Tissue Culture

May 17th, 2014

Tissue culture is a biological method of asexual propagation where a very small piece of tissue (shoot apex, leaf section, or even an individual cell) is excised (which is known as Explants) and placed in sterile /aseptic culture in a test tube/petri dish/tissue culture container containing a special culture media.

A tissue culture is used for rapid multiplication of an organism. A very specialized laboratory with sterile/aseptic conditions is required for tissue culture. All the procedure involved in tissue culture should be carried out in a special ventilated cabinet and these conditions are provided by Laminar Air Flow.

The culture medium is a proper mixture of the nutrients (organic and inorganic), vitamins, sugars, minerals and plant hormones especially Cytokinin and Auxin for shoot and root initiation.

Steps involved in Tissue Culture are

Explants ; excision of the plant parts.
Place the explants in a tissue culture container/test tubes/petri dishes.
Multiplication ; Tissue grows and produce small plants.
Rapid multiplication by transfer of fresh culture.
Transplanting the plant into some kind of acclimation container.

Laminar Air Flow provides a work area with aseptic/sterile conditions for the tissue culture. Laminar Air Flow has continuous displacement of air (it provides streamline flow of air) that passes through HEPA (High Efficiency Particulate Air) filter that removes the particulates from the air.

Laminar Air Flow are equipped with a UV lamp that should be turned on about 10-20 minutes before being used to sterilize the shell or cabinet or the surface of the Laminar Air Flow to avoid any kind of contaminations. Wipe down the surface with ethanol before and after each use.

Laminar Air Flow can be vertical and horizontal. In the Vertical Laminar Air Flow the air blows down from the top of the cabinet. Vertical Laminar Air Flow is best for working with hazardous specimens since the aerosols that are generated in the cabinet are filtered out before they are released into the surrounding environments.

Horizontal Laminar Air Flow are designed such that the air flows directly at the operator hence they are not useful for working with hazardous specimens but are best protection for Tissue/cell culture.

Laminar Air Flow provides aseptic/sterile conditions for the preparation of Culture Media. All the culture vessels, test tubes, pipette, tip boxes, stocks of sterile eppendorfs should be opened only in the Laminar Air Flow to avoid any kind of contaminations. Culture Media cannot be prepared outside the Laminar Air Flow because it can get contaminated and there would not be any result.

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What is Laminar Hood/Laminar Air Flow?

May 17th, 2014

Laminar Hood sometimes also known as Laminar Air Flow is an enclosed bench designed to prevent contaminations like biological particles (SPM) or any particle sensitive device. This closed cabinet is usually made up of stainless steel without any gap or joints where spores might collect.

Air is drawn through a High Efficiency Particulate Air (HEPA) filter and blown in a very smooth flow or streamline flow (when a fluid flows in a parallel layer with no disruption between the layers)

Laminar Hoods are equipped with a shortwave ultraviolet germicidal lamp to sterilize the shell or cabinet or the surface of the Hood. The Hoods should be turned on about 10-20monutes before being used to kill the germs. It is important to switch off this light during use as it may cause mutations and may give any exposed skin sunburn and may cause cataracts too. It is required to wipe down the cabinet surface with ethanol before and after use and it’s also required to keep the hood free of clutter as possible because this will interfere with the laminar flow air pattern.

Components of the Laminar Hood are

A Blower
High Efficiency performance Air filter
A Plenum Chamber (Pressurized housing containing air at positive pressure)

Why you need Laminar Hood?

It provides clean air to the working area.
It provides a constant flow of air out of the work area to prevent room air from entering.
The air that flows out from the Hood, removes contaminants introduced into the work area by personnel.

The most important part of a laminar flow hood is a High Efficiency Particulate Air filter (HEPA). Room air is taken into the unit and passed through a pre-filter to remove gross contaminants (lint, dust etc). The air is then compressed and channeled up behind and through the HEPA filter in a laminar flow fashion. The HEPA filter removes nearly all of the bacteria from the air.

What Safety Precautions should be taken for the Laminar Hood?

Large objects should never be placed near the back of the hood. These objects contaminate everything downstream and disrupt the laminar flow pattern of air too, which normally suspends the contaminants and removes them from the area.
Waste and other items should never enter the hood. All calculations should be done before entering the hood. And clutter should be less.
Hands should be cleaned by ethanol.Do not touch your hair, face or clothing while working.
Excess dust should be removed from items before introducing them into the hood.

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Food Industry and Clean Benches (Laminar Air Flow)

May 8th, 2014

Main aim of all the food industries is to insure the safety of food that involves the careful control of process from the farm gate to the consumer. Safety includes control of both chemical and microbiological characteristics of the products. Most processing places emphasis on microbial control and often has its objective, the elimination of organisms or prevention of their growth.

Some of the aims of the food processing industry are

To make food safe ( microbiologically and chemically)
To provide products of highest quality ( flavor, color, texture)
To convert/make food into that forms that are convenient ( ease of use)

Items/points that should be controlled in food industry are

Microorganisms
Enzymes
Chemical reactions ( safety from a chemical viewpoint generally relates to keeping undesirable chemicals such as pesticides, insecticides and antibiotics our of the food supply)
Physical structure
Water activity

Clean bench/Laminar Air Flow is one of the major processes that are aimed at prevention of growth of microorganism. Laminar Air Flow/Clean Bench provides product protection by ensuring that the work in the bench is exposed to only HEPA filtered air. These are recommended for work with non hazardous materials where clean, particle-free air quality is required. Main aim is to keep the food product sterile and free of contamination.

Laminar Air Flow/Clean bench has its own filtered air supply, and are equipped with HEPA filters. HEPA filter removes particulates such as microorganisms, but it does not remove vapors/gases.

HEPA filters are made up of Boron Silicate Microfibers formed into a flat sheet by a process similar to making papers.
Flat filter sheets are pleated to increase the overall surface area.
Pleats are separated by aluminum baffles which direct the air flow through the filter.

Depending on its quality a HEPA filter can trap from 9,997 to 9,999 of every 10,000 particulates of a diameter greater than and less than 0.3 micron.

In the Baker (food) industry, HEPA filters used are leak free and rated at 99.99% performance level. But the Laminar Air Flow/Clean Bench does not provide protection to personnel or to the ambient environment and even it is not designed to contain aerosols generated by procedure; the user is exposed to these aerosols.