Follow
1.0 OBJECTIVE : To lay down the procedure for the preparation and storage of culture media. Preparation of the Culture media for microbial growth is an important step in detecting microbes in raw materials, finished products, intermediate products, water and environment. Proper preparation of the media and employing it for microbial testing will ensure the validity of the result.
2.0 SCOPE : This SOP is to be followed in the preparation of the media in microbiology laboratory of Quality Control Department of Track-II facility of (Company Name).
3.0 RESPONSIBILITY
3.1 Each individual in the laboratory is responsible for carrying out the procedure.
3.2 Overall responsibility for training, implementation & follow-up with the QC Manager or his nominee.
4.0 ACCOUNTABILITY
4.1 Head of Quality.
5.0 PRECAUTIONS
5.1 Disinfect hand with filtered 70% IPA before media preparation.
5.2 Check calibration of the balance before weight the media.
6.0 PROCEDURE
6.1 Procurement of dehydrated culture media
6.1.1 Dehydrated media should be procured from authentic sources.
6.1.2 The media must be provided with the certificate of analysis.
6.1.3 The date and source of procurement should be entered in the media receipt and usage log book (Annexure – I.).
6.1.4 Check the labels on the containers for Name of media, Manufacturing date and Expiry date.
6.1.5 Label the dehydrated media containers with date of receipt and received by.
6.1.6 The media should have minimum available shelf life of one year at the time of receipt.
6.2 Storage of dehydrated media
6.2.1 Dehydrated media should be stored as mentioned on the label. If not specified the media should be stored at a temperature not exceeding 25°C.
6.2.2 If the container of dehydrated media is opened, seal the container by wax coating (Para-film) to avoid denaturation of the media.
6.2.3 The dehydrated media should be used within twelve months after opening the container. At that time the medium must be within the supplier’s shelf life.
6.2.4 If any abnormality such as lump formation, color darkening, color change is observed even within the shelf life, the medium will be discarded.
6.3 Preparation of media
6.3.1 Calculate the quantities of dehydrated media required for media preparation as follows:
Weight of Dehydrated media (gm) = Volume of media required (ml) X Weight of media per 1000 ml (As specified on the label)
1000
6.3.2 Purified water should be used for preparing the media.
6.3.3 Take suitable container and add purified water approximately half of the volume of media to be prepared.
6.3.4 Open the dehydrated media container and weigh calculated quantity of media.
6.3.5 After weighing the media, tightly secure the lid of the dehydrated media container. If pouch pack is being used, fold the mouth of pouch and place a U-clip over the folding and keep the pouch in a self-sealing polybag.
6.3.6 Add the weighed media into the container already containing water. For media containing agar, add dehydrated media into boiling water.
6.3.7 Make up the volume by adding Purified Water gradually with gentle shaking followed by heating on water bath and ensure clumps are not formed.
6.3.8 Check the pH and adjust to required pH (as specified on the label of the dehydrated media) with either solution of 0.1N NaOH or 0.1N HCl.
6.3.9 All the data should be recorded in the Annexure – II
6.3.10 Dissolve the media by swirling the container. Take care that media should not splash.
6.4 Sterilization of prepared media
6.4.1 Sterilize the media at the validated media cycle at 121°C for 20 minutes. Do not store the prepared media before sterilization for more than 2 hours.
6.4.2 Assign a batch number to the prepared media as given below:
XXXXX
Where,
XXXXX : Sterilized media lot (eg. 00001or 99999)
6.4.3 Aseptically dispense (under Laminer Air Flow) a small quantity of sterilized cooled media in a glass vial and check the pH of media. Adjust if necessary with either sterile solution of 0.1N NaOH or 0.1N HCl.
6.4.4 For the media, which are thermo labile, sterilize the media as per the instruction as specified on the label. Note down the procedure followed for thermo labile media.
6.4.5 All the data should be recorded in the Annexure – III.
6.5 Dispensing of prepared media
6.5.1 After preparation the media should be maintained in the water bath at 45°C to 55°C, which should be used within 08 hours.
6.5.2 For preparation of media plate, pour aseptically approximately 15-20 ml of media cooled at around 45°C. Allow the plate to solidify under LAF.
6.5.3 For preparation of slant dispense 4-6 ml of sterile media into test tubes and allow solidifying after keeping it in a slanting position.
6.6 Storage of prepared media
6.6.1 Store the prepared media plates and slants at a temperature not exceeding 25°C.
6.6.2 Prepared media plates, tubes and slants are used within 10 days from the date of preparation.
