Aseptic - free from contamination caused by harmful bacteria, viruses or other microorganisms
However why is it so important to keep an experiment aseptic? Especially in an experiment like ours, where we were trying to see the growth of particular bacteria which we had intentionally scraped onto our agar. If any other bacteria were to get on the agar plate they would compete for the same nutrients and space as the intended bacteria. This would mean our results would be inaccurate and unreliable. Generally if we are trying to study and measure the growth of a specific bacteria we would not want to introduce new bacteria which would compete with the intended bacteria.
How to make an experiment aseptic
However why is it so important to keep an experiment aseptic? Especially in an experiment like ours, where we were trying to see the growth of particular bacteria which we had intentionally scraped onto our agar. If any other bacteria were to get on the agar plate they would compete for the same nutrients and space as the intended bacteria. This would mean our results would be inaccurate and unreliable. Generally if we are trying to study and measure the growth of a specific bacteria we would not want to introduce new bacteria which would compete with the intended bacteria.
How to make an experiment aseptic
- Before starting the experiment and turning on your Bunsen burner, wipe down the work surface and the tray with ethanol. This sterilises the surface (ethanol sterilises the surface as it interacts with the lipid membrane of bacteria which kills the microorganisms)
- Then light the Bunsen burner. This causes an updraft meaning the bacteria and microorganisms in the air will not land on the specimen you are trying to keep sterile. The effect of this is within a 30cm radius.
- Flame your inoculating loop between every smear, this sterilises the utensil as the bacteria (unintended) may get onto the loop as you hold it and move it around, to get rid of this bacteria that will contaminate the experiment. It is important to heat the metal until it is red hot as this the correct temperature. The heat will kill the bacteria the heat denatures the proteins inside the bacteria.
- When opening a test tube or conical flask with a sterile specimen inside, pass the neck through the flame, this heats up the neck meaning the air flows out of the bottle due to convection currents. This means minimal air is flowing into the sterile flasks meaning there is less chance of airborne bacteria contaminating the sterile specimen
- When using the petri dish open the top as little as possible and try shield the Petri dish. This is done so the volume of airborne bacteria contaminating the petri dish is minimised
- When taking the lid off of a sterile specimen do not put it down, even on the sterile surface, ideally keep it in the hook of your small finger.
- It goes without saying, the longer the experiment takes the more likely it is that there could be contaminants, so be sure to work quickly but safely, to help this, ensure everything you may need to at your work surface before you open any sterile containers.