Product Description

 REAGEN The total colony refers to the total number of colony contained in 1 mL(g) sample or unit area sample after the sample is treated and cultured under certain conditions, and is the most commonly used microorganism detection item. REAGEN total colony test petrifilms are prefabricated ready-to-use medium products, containing standard nutrient medium, water-soluble absorbent gel and chromogenic agent. The colony appear red on the test petrifilms, which can shorten the counting time and enhance the counting effect.

Kit Contents, Storage and Shelf Life

The REAGEN  Total Colony 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 6.8and 7.2, 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 total colony  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 petrifilms, then cover the upper film slowly, pay attention to avoid bubbles during this process, let the medium solidified for about 2minutes, 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 24 to 48 hours,  aquatic products were cultured at 30±1℃ for 72±3h, then the results could be read. No more than 10 coliform test petrifilms were stacked and cultured.

Interpretation of results

Count all red colony regardless of size and clarity,  appropriate counting ranges from 30 CFU to 300 CFU. If the entire culture area is light red, the concentration of bacteria may be too high, and the sample need to be further diluted to obtain an exact count. If you need to separate the colony, uncover the upper membrane and use the inoculation needle to pick out the colony.