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Monday, 23 February 2015

In microbiology why petriplates are incubated in inverted positon?

In microbiology, petriplates are used for different testings like MLT of products and water etc. After completion of the test petriplates are incubated in an inverted conditions in incubators. What is the reason behind incubation of petriplates in an inverted  position and what are the benefits of incubation of of these petriplates in inverted position? Here I would like to explain this.

Petriplates incubated in inverted position
First thing is that, media should be poured in to petriplates at specific temperature which means media should not be very hot during testing to cause damage of microorganisms and media should not be cool to become solidified before pouring. That's why media should be poured in to petriplates when temperature is at about 45° C. During incubation, media contains moisture and if petriplates are incubated in upright position then moisture will evaporate from the media and that moisture condense on the lid in form of droplets.

Moisture on lid of the Petriplate 

When condensed moisture fall on the media plates then it can cause spreading of microbial colonies and it would be difficult to count the number of colonies properly. So, to prevent this petriplates are incubated in an inverted position. There are also other reason as well like handling of petriplates would be more easy in case  of inverted position because in upright position chances of opening of petriplates would be more during handling. That's why petriplates are incubated in inverted positions.

Thanks!

3 comments:

  1. How do you prevent excess moisture accumulation on the petriplate lid?

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    Replies
    1. Excessive moisture accumulation on lid is caused when media poured at higher temperature.So, just check the temperature of the media while pouring and temperature should be around 45°C while pouring the media.

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  2. sir please explain about area qualification
    what is area qualification / microbiological lab qualification
    thanks

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