The nutrition medium prepared by manual work is called culture media in microbiology, which is to help microorganisms to develop, breed and accumulate metabolites. The medium in microbiology usually includes water, nitrogen source, mineral salt with micro elements, carbon source, growth factor with vitamin, amino acid, basic group, antibiotics, pigments, hormone and serum and many more.
Since we have mastered the basic knowledge of medium in microbiology, what should we pay attention to when we prepare, sterilize and use the media. The following notes are for you to pay more attention to in your daily work:
1. The preparation of media should follow the principle of FIFO (first in first out). Every media should be noted with date of opening and expiration. Generally after opening the effective date of media is one year.
2. Before preparing the media you should check out whether the date of manufacture is within the date of expiration or not. And check the date of expiration and the air tightness of opening. You should make sure that the substance doesn't go bad and damp.
3. When preparing the media you should weigh each components precisely according to the forum of media or instructions. It is necessary to balance the PH after the media has been dissoluted and mixed. You can use the precision test paper or acidimeter to measure PH. You balance the PH to a proper realm with sodium hydroxide and hydrochloric acid in one mol per litre.
4. Rwady-made preparation and sterilization must be assured for medium in microbiology. Prepared but not be sterilized media should not be placed for long time even overnight.
5. Constant temperature and pressure should be assured when sterilizing. And the time of sterilization should be effective. Different culture media for food microbiology has different sterilization conditions, so when you sterilize you must do it according to the instruction. Otherwise the results would be different.
6. After sterilization the media should be stored in the refrigerator in 4 degree centigrade.
It should be wrapped up with plastic bag and stored in the refrigerator to be made flat. It is assured by experiment that the sterilized media could be kept for one month in 4 degree centigrade in the refrigerator. When you use it, please follow the principle of FIFO.
7. Melt the media according to the application amount on that day when using it. Don't melt the media repeatedly. You can melt the media by putting it into the boiling water, or by ways that have the same effect like laminar flow of stream in the pressure cooker.
8. Put the melted media into the water bath kettle with constant temperature to cool it off and keep it warm. The melted media should be used immediately. The melted media should not be placed for four hours.
9. The temperature of dumping media should be around 45 degree centigrade when testing the microbiology in the products. The temperature should not be too hot to kill the bacterium or too cold that the caky media cannot be used for experiment.
10. The additive should be added when the temperature of media is around between 47 and 50 degree centigrade for it is unstable to heat. Before adding it should be placed to the indoor temperature and subpackaged into the stand-by vessels as soon as possible.
11. Take concentrated samples to the greastest extent so that the frequent opening of a bottle of media is avoided. Otherwise the rate of media contamination increases, leading to errors in the experiment result. The entire operation of dumping media should be done besides the flame of alcohol lamp so that it can avoid the contamination of infectious microbe.
12. Every bottle of medium in microbiology should be made blank control trial.