Aseptic Techniques

Noadswood Science, 2012

Aseptic TechniquesTo know how to test for bacteria in food using aseptic

techniques

Wednesday, April 19, 2023

Aseptic Techniques

Aseptic techniques prevent contamination when preparing and carrying out microbiological experiments

The procedure involves sterilisation and specific aseptic practical techniques…

Work is carried out close to a Bunsen flame (the convection current prevents potentially contaminating particles falling onto the agar plate) and all apparatus is sterilised before use…

Aseptic Techniques

The main principle behind aseptic techniques is that conditions are sterile (eliminating any form of microbial life)

Inoculating loop is heated in the Bunsen and the agar plate remains nearby preventing unwanted microbial life landing on the agar plate…

Growing Micro-organisms

Micro-organisms are grown in a culture medium containing carbohydrates, minerals, proteins and vitamins – this is usually agar in a petri dish.

To grow a micro-organism scientists need to: -

1) Sterilise the culture medium and petri-dish (done in an autoclave)

2) Use sterile inoculating loops (pass through a flame) to transfer micro-organisms

3) Seal the dish with adhesive tape to prevent micro-organisms from the air contaminating the sample / culture

Experiment

You are going to swab different areas of the school to ‘obtain’ bacteria, then using an agar plate we are going to grow this bacteria to see what types exist and in what abundance…

Before we start the experiment you need to complete the risk assessment to consider what risks are involved with swabbing for bacteria and then growing them…

The Student Safety Sheets will aid you in writing up your risk assessment

Risk Assessment

Consider the hazard (what can hurt you) and the risk (the likelihood of this happening) as well as how you can minimise the risks, what emergency action you should take if there is a problem and any after use / hazard symbols associated…

Laboratory Swab

Your task is to swab a variety of areas to test what bacteria are present…

Identify 5x areas you want to test for and then using a cotton bud swab the area (e.g. the science lab / toilet / your finger nails etc…)

Gently drag the cotton bud over the agar plate, and quickly seal it (have the agar plate near a Bunsen at all times)