Product Description

 REAGEN Coliform is aerobic and facultative anaerobic gram-negative non-bacillus that can ferment lactose, produce acid and gas under certain culture conditions, and are the most commonly used microbial detection items. The REAGEN Coliform Test Petrifilms is a pre-made, ready-to-use medium containing modified VRB medium, cold water-soluble absorbent gel, and chromogenic agent to enhance colony counting.This test petrifilms is suitable for the determination of coliform in all kinds of food and food raw materials.

Kit Contents, Storage and Shelf Life

The REAGEN Coliform Test Petrifilms has  the capacity  for25 determinations. The shelf life  is 12 months when the kit is properly stored.

Sample Pretreatment

1.Take 25 g(mL) of sample into a sterile homogenizing cup or bag containing 225 mL phosphate buffer (or normal saline), and mix it with a homogenizer for 1 to 2 min to make a sample homogenizing liquid of 1:10.

2.The pH of the sample homogenate should be between 6.5 and 7.5, and adjusted with 1mol/LNaOH or 1mol/L HCl, respectively, if necessary.

3.Use 1 mL sterile straw or pipette to absorb 1 mL 1:10 homogenized liquid, inject it into a test tube containing 9 mL diluent, shake it to become 1:100 sample homogenized liquid, and so on, prepare a 10-fold series of diluted sample homogenized liquid, and replace it with 1 mL sterile straw or suction head every time the dilution is increased.

4.The whole process from the preparation of sample homogenate to the completion of sample inoculationshould not exceed 15min.

Inoculation

According to the estimation of the contamination status of the sample, 2 to 3 sample homogenates with appropriate dilution (liquid samples can include the stock solution) are selected for testing. Place the coliform test petrifilms on a flat experimental table, uncover the upper film, absorb 1 mL of sample droplets with a sterile straw and add them to the center of the test tablet, then cover the upper film slowly, pay attention to avoid bubbles during this process, let the medium solidified for about 2-5 minutes, and inoculation two pieces per dilution. At the same time, 1 mL of blank diluent was absorbed and added into two sterile test petrifilms for blank control.

Cultivate

After inoculation, the transparent surface of the test petrifilms was placed horizontally upward in a constant temperature incubator and incubated at 36±1 ° C for 18 to 24 hours, then the results could be read. No more than 20 coliform test petrifilms were stacked and cultured.