Products

Principle

XLT4 Agar Base is a differential medium, slightly selective for the detection of pathogenic enterobacteria, especially non-typhi Salmonella species. Media is composed of Proteose peptone, yeast extract, xylose, lysine, lactose, sucrose, sodium chloride, sodium thiosulphate, ferric ammonium citrate, phenol red, and agar. Proteose peptone and yeast extract provides sources of nitrogen and carbon, as well as vitamins and cofactors required for growth. Xylose, lactose and sucrose are the carbon source. Xylose is fermented by most enteric organisms except Shigella and Providencia. Sucrose and lactose provide sources of fermentable carbohydrate. Lysine is also added to differentiate Salmonella, which undergoes decarboxylation to cadaverine. Sodium chloride maintains osmotic balance in the medium. Phenol red is pH indicator. Agar is a solidifying agent. In medium as the concentration of xylose is declined, the Salmonella organism’s decarboxylate lysine causing is version to alkaline conditions. The resulted alkaline reversion by lysine-positive organisms is prevented by acid produced by the fermentation of lactose and sucrose. Simultaneously, the sodium thiosulfate is metabolized to hydrogen sulfide and reacts with ferric ammonium citrate which acts as indicator of hydrogen sulfide production under alkaline conditions. The hydrogen sulfide producers are detected by darker colonies, due to the ferric sulfur precipitate. Due to xylose, lactose or sucrose fermentation produce the acidification and lysine decarboxylation to cadaverine causes alkalization and consequently the phenol red indicator turns to red. Salmonella are differentiated on basis of ferrous sulfur precipitation. The Salmonella colonies show red colored with black centers. XLT4 supplement (Tergitol 4) inhibit the growth of gram-positive bacteria and certain gram-negative bacteria other than Salmonella.

Use: Recommended for the isolation and enumeration of non-typhi Salmonella species.

Proteose Peptone

1,60 g/L

Yeast Extract

3,00 g/L

Xylose

3,750 g/L

L-Lysine

5,00 g/L

Lactose

7,50 g/L

Sucrose

7,50 g/L

Sodium Chloride

5,00 g/L

Sodium Thiosulphate

6,80 g/L

Ferric Ammonium Citrate

0,80 g/L

Phenol Red

0,080 g/L

Agar

18,00 g/L

pH at 25°C

7,4±0,2

Formula adjusted for optimum performance and parameters

Storage and Shelf Life: The product is highly hygroscopic; keep the container tightly closed at all times and store it properly as per the conditions mentioned on the label. The declared expiry is valid only when stored as per the conditions mentioned on the label.

Note: Sterilize media immediately after reconstitution.

Disposal: To avoid the contamination or propagation of any hazardous microbes the used, unusable or modified preparation of this product must be disposed after autoclaving after completion of task.