Yeasts & Moulds Water Analysis

Molds and yeasts are widely found in the air, water and soil, most of them are harmless to human body, but some of them are harmful to human body, such as Aspergillus flavus, which secretes aflatoxin, a strong carcinogen. Mold inadvertently consumed will stimulate the human digestive tract, stomach, etc., and in serious cases can also damage the liver, causing food poisoning. And we usually use mold yeast test tablets for analysis and testing. Compared with the traditional method, it eliminates a lot of auxiliary work such as preparation of culture medium, disinfection and cleaning treatment of culture vessels, and can start sampling and testing at any time, and it is easy to operate, and through the amplification of enzyme chromogenic agent, the colonies are clearly shown in advance, and the culture time is shortened from one week to 48-72 h.

Testing Services

BOC Sciences performs yeast and mold testing with microbiological test sheets, which are supported by a lightweight waterproof paper material covered with a dry culture substrate (nutrients, coagulant, selective inhibitor, color developer) and a transparent water barrier film. The scientifically calculated culture substrate can absorb 1 mL of sample solution to form a gel layer, and the enzymes produced by microbial growth and metabolism hydrolyze the chromogenic agent to develop the color of the colony.

Testing Procedure

Sample preparation

Put the sample into a sterile homogenate cup or bag with phosphate buffer, mix evenly to make sample homogenate, and adjust the pH of sample homogenate to 6.8~7.2 with sterile NaOH or HCl solution if necessary. The homogenate was sucked out with a sterile pipette or pipette, injected into a test tube containing dilution solution, shaken into 1:100 sample homogenate, and so on to prepare a 10-fold series of diluted sample homogenate.

Inoculation

Select 2 to 3 dilutions for testing according to the estimation of the sample contamination status. Place the mycobacterial yeast test strip on a flat laboratory table, remove the upper membrane, add a drop of sample homogenate to the center of the test strip with a sterile pipette, and slowly cover the upper membrane to avoid air bubbles. Allow to stand for 3~5 min to allow the sample to diffuse and re-form the gel.

Incubation

Place the test strip horizontally with the front side up and incubate for 48 h-72 h.

Readings

Count all blue-green colonies, regardless of size and clarity. Light blue-green raised colonies are yeast, blue-green flat colonies are mold. If the entire culture area is pale blue-green, the concentration of bacteria may be too high and the sample needs to be further diluted to obtain an exact count. If you need to isolate colonies for further analysis, remove the upper membrane and use an inoculating needle to pick out the colonies for use.

Additional notes

As mold is often spread everywhere in the air in the form of spores, and a variety of samples are required mold yeast must not be detected, so the detection of mold requires special care in the operation, sampling supplies, dilution water and pipette tips need to be carefully sterilized, inoculation, try to avoid air flow, clean action, each time it is best to use sterile water to connect two blank control, to avoid false positive results.