Eugon LT 100 Agar

This medium contains ingredients that neutralize inhibitory substances present in the sample, such as lecithin and polysorbate 80.

L-Cystine and sodium sulfite are added to stimulate growth. Pancreatic digest of casein and papainic digest of soy bean provide nitrogen, vitamins, minerals and amino acids essential for growth. Glucose is the fermentable carbohydrate providing carbon and energy. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Bacteriological agar is the solidifying agent.

ISO 21149 recommends inoculating the initial suspension of the sample of the cosmetic product in a selective liquid medium with neutralizing and dispersing agents (Eugon LT 100 Broth, LC-2110).

Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.

Preparation

Suspend 51.4 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Sterilize in autoclave at 121 °C for 15 minutes. Cool to 45-50 °C and dispense into Petri dishes.

Instructions for use

1. Prepare the initial suspension from 1 mg or 1 mL of the sample and 9 mL of enrichment broth (1:10 dilution). Use a solubilizer if the sample is immiscible.
2. Incubate at 32.5 ± 2.5 °C for at least 20 h.
3. Transfer a defined amount of initial suspension to a Eugon LT 100 Agar plate. This step can be carried out by inclusion method, by seeding on the surface or by membrane filtration.
4. Incubate the inverted plates at 32.5 ± 2.5 °C for 72 ± 6 h.
5. Perform the colony count.

Due to the composition of Eugon LT 100 Agar and its hygroscopic properties, the powder could appear lumpy and moist. This phenomenon does not affect the microbiological performance of the medium.

• ISO 21149:2006 Cosmetics - Microbiology - Detection and counting of mesophilic aerobic bacteria.