search

Desiccation of Agar Plates

Desiccation of Agar Plates
17/08/2017

The biggest issue facing operators when exposing settle plates in high airflow environments, such as laminar airflow cabinest; class II microbiology safety cabinets and isolators, is the desiccation of the medium during the four-hour exposure time, which is the maximum recommended exposure time. It is important during exposure that the agar does not shrink from the edge of the petri dish or crack down the middle. This is to ensure the maximum surface area is constantly exposed to the environment. Possibly more importantly, is that the agar is still able to show good recovery of your regular test organisms; both post exposure and post incubation1.

Reducing the effect of desiccation of agar Selecting media fill volume You cannot avoid the desiccation of agar. An agar plate exposed in a LAF running at 0.45m/s ±20% for four hours is going to desiccate. The Redipor range of irradiated agar comes in a number of fill volumes to meet the needs of your working environment:

18ml is the standard fill volume for 90mm petri dishes 27ml is our deep filled equivalent. This is the most popular for high air flow environments 32ml is our extra deep fill and also the maximum we can fill to. These are for environments where dehydration is a real problem Assessing operating environment In regards to how the agar shrinks, ideally it will shrink downwards before it shrinks inwards. If there is excessive shrinkage even in deep filled plates, there may be issues with your operating environment, i.e. the airflow is too high and/or the air is too warm - I call this the hair dryer effect! If you cannot alter this, then you may need to replace your settle plates every couple of hours rather than waiting the full hour hours.

CONTACT US TO DISCUSS YOUR MEDIA REQUIREMENTS Selecting media formulation We are aware of issues where the agar cracks down the middle as it shrinks. This may happen with irradiated media containing disinfectant neutralisers, more so in high airflow environments. Should this happen, perhaps you should reconsider the use of neutralisers in your settle plates? Neutralisers are necessary in petri dishes when they are used as glove dabs or streaking swabs. Are neutralisers necessary in media for passive air sampling?

Hopefully the above is good advice for helping you choose the appropriate fill volume and formulation. If you have any further queries or comments, we are happy to assist you.

For more information on  Desiccation of Agar Plates  talk to  Cherwell Laboratories Ltd

Enquiry Form



More News

CHERWELL TO INTRODUCE NEW REDIPOR® BROTH KIT AT APDM

CHERWELL TO INTRODUCE NEW REDIPOR® BROTH KIT AT APDM

New Redipor Universal Operator Broth Transfer Kit provides all key elements needed for operator aseptic broth transfer testing Bicester, UK, 20th June...

Read More
Reducing risk from bacterial endospores in aseptic preparation supported by Cherwell

Reducing risk from bacterial endospores in aseptic preparation supported by Cherwell

Bicester, UK, 15th June 2015: Cherwell Laboratories specialist providers of products for process validation and environmental monitoring, have highlig...

Read More
CHERWELL ANNOUNCES NEW CLEANROOM MICROBIOLOGY FOCUSED WEBSITE LAUNCH

CHERWELL ANNOUNCES NEW CLEANROOM MICROBIOLOGY FOCUSED WEBSITE LAUNCH

Bicester, UK, 30th January 2019: Cherwell Laboratories, specialist suppliers of environmental monitoring and process validation solutions for the phar...

Read More

Read More

Read More

List your business

Would you like to register your company on one of the UK's largest and most effective Trade websites?

Are you looking for a reliable and consistent source of enquiries from your industry sector? Would you like to see why Find the Needle clients come back year after year to use our service? If so then feel free to register using the link 'here'.

Register
Office Address: