1. Principle & application Scope

Bacillus cereusis widely distributed in the natural world and could produce thermal stability toxin in certain condition. People who suffer from food poisoning of bacillus cereus would have the symptom of nausea, vomit, and diarrhea, etc.Bacillus cereus count plate which adopts imported selective medium and specific enzyme chromogenic reagent is a kind of disposable rapid test product that can greatly simplify detection process (the whole process takes less than 24 hours). Bacillus cereus count plate which is easy to use and very convenient could be widely used in institutes of food hygiene inspection and food factories.

Executive standard: Food sanitary microbiology test, bacillus cereus test (GB/T 4789.14). 

2. Using method

2.1 Sample preparation: Prepare the 1:10 solution by placing 25g or 25mL sample into 225mL sterile saline, then prepare 1:100 solution by pipetting 1ml 1:10 solution into 9ml sterile saline.

2.2Inoculation: Place the bacillus cereus count plate onto sterile experiment table, uncover the film on the surface. Suck 1mL solution with sterile pipette ,and then drop slowly and evenly onto the plate. Then,cover the film gently and stand it for 10s to let the medium solidify. Inoculate two count plates for each dilute ratio sample solution. And do a blank control test.

2.3 Culture: Pile up the plates together and place them back to the ziplock bags and seal them well. Place them in the incubator with transparent side up. The quantity of superimposed count plates should not be more than 12.  The temperature of culture is 36℃±1℃, and the time of culture is 15-24h.

3. Results

Colony of bacillus cereus would show bluish green after the culture. The sample which shows  positive result should be veritified by other detection methods or take the sample to do at least one more test using bacillus cererus count plate.

4. Additional explanatory note

4.1This product has high sensitivity and specificity with typical bluish green color of bacillus cereus colony, other types of bacteria can’t grow on the plate.

4.2Detection lower limit of bacillus cereus count plate reaches 1CFU/mL.

4.3Pay attention that used count plates should be treated timely according to biology safety waste treatment rule because there are live bacteria on them.