Microbiologists have attributed problems encountered with contaminants while working in the lab. Especially when streaking or pour plating or even subculturing. How long can prepared plates be exposed for contaminants from air to contaminate?
Hello,
The answer depends on the direction that the air is taking and the quality of the air. If the air blowing straight there is less chance of deposition than if the air is turbulent. Furthermore, if the air strikes an object, then there is a greater risk of particles falling out of the air. In addition, the more contamination, then the greater chance of microbial deposition.
With these variables considered, between 5 and 10 seconds. After this time, the risk increases.
It will obviously depend on the plate location (moving or quiet air room) and the bacterial load of the air itself, but even in this case you'll need quite a few hours to get a heavy load of bacteria in your plate.
If you want to know how long does it take to contaminate an open plate it can be done in few seconds if manipulation is not correct. Try to open close to a bunsen and keeping distance from breath, skin and/or dusty places).
Hope this helps.
Agreed with all the above comments. However during working in lab, it is advisable to open the lid of Petriplate to an angle minimum as possible to carry out spreading or pouring or streaking activity. ( 45 to 55 degree)
A previous question may consider any kind of contamination, or a representative contaminatios. In first situaion, few minutes, in second case, 1 or 3 hours. The other consideration, referring o the level of environmental contamination and air movement, for instance, will also be important.