Principle of Xylose lysine deoxycholate agar (XLD agar) II Microbiology II Media principle
XLD agar Principle (Xylose lysine deoxycholate agar)
Sugars xylose, lactose and sucrose provide sources of fermentable carbohydrates, xylose is mainly incorporated into the medium since it is not fermented by Shigellae but practically by all enterics. This helps in the differentiation of Shigella species.
Salmonellae rapidly ferment xylose and exhaust the supply. Subsequently lysine is decarboxylated by the enzyme lysine decarboxylase to form amines with reversion to an alkaline pH that mimics the Shigella reaction. However, to prevent this reaction by lysine-positive coliforms, lactose and sucrose are added to produce acid in excess. Degradation of xylose, lactose and sucrose to acid causes phenol red indicator to change its colour to yellow.
Bacteria that decarboxylate lysine to cadaverine can be recognized by the appearance of a red colouration around the colonies due to an increase in pH. These reactions can proceed simultaneously or successively, and this may cause the pH indicator to exhibit various shades of colour or it may change its colour from yellow to red on prolonged incubation. To add to the differentiating ability of the formulation, an H2S indicator system, consisting of sodium thiosulphate and ferric ammonium citrate, is included for the visualization of hydrogen sulphide produced, resulting in the formation of colonies with black centers. The non-pathogenic H2S producers do not decarboxylase lysine; therefore, the acid reaction produced by them prevents the blackening of the colonies. XLD Agar is both selective and differential medium. It utilizes sodium deoxycholate as the selective agent and therefore it is inhibitory to gram-positive microorganisms.
Видео Principle of Xylose lysine deoxycholate agar (XLD agar) II Microbiology II Media principle канала BioMagica
Sugars xylose, lactose and sucrose provide sources of fermentable carbohydrates, xylose is mainly incorporated into the medium since it is not fermented by Shigellae but practically by all enterics. This helps in the differentiation of Shigella species.
Salmonellae rapidly ferment xylose and exhaust the supply. Subsequently lysine is decarboxylated by the enzyme lysine decarboxylase to form amines with reversion to an alkaline pH that mimics the Shigella reaction. However, to prevent this reaction by lysine-positive coliforms, lactose and sucrose are added to produce acid in excess. Degradation of xylose, lactose and sucrose to acid causes phenol red indicator to change its colour to yellow.
Bacteria that decarboxylate lysine to cadaverine can be recognized by the appearance of a red colouration around the colonies due to an increase in pH. These reactions can proceed simultaneously or successively, and this may cause the pH indicator to exhibit various shades of colour or it may change its colour from yellow to red on prolonged incubation. To add to the differentiating ability of the formulation, an H2S indicator system, consisting of sodium thiosulphate and ferric ammonium citrate, is included for the visualization of hydrogen sulphide produced, resulting in the formation of colonies with black centers. The non-pathogenic H2S producers do not decarboxylase lysine; therefore, the acid reaction produced by them prevents the blackening of the colonies. XLD Agar is both selective and differential medium. It utilizes sodium deoxycholate as the selective agent and therefore it is inhibitory to gram-positive microorganisms.
Видео Principle of Xylose lysine deoxycholate agar (XLD agar) II Microbiology II Media principle канала BioMagica
Показать
Комментарии отсутствуют
Информация о видео
Другие видео канала
![Principle of MacConkey’s Agar II Microbiology II Media principle](https://i.ytimg.com/vi/zw29k7mp3i8/default.jpg)
![GRAM STAINING | Bacterial Staining Technique | Microbiology | Vivek Srinivas | #Bacteriology](https://i.ytimg.com/vi/--OvDvS-Pec/default.jpg)
![XLD agar salmonella-Shigella Colony Characteristics(Xylose Lysine Deoxycholate Agar)](https://i.ytimg.com/vi/AJ91FTLHS_Q/default.jpg)
![Eosin methylene blue agar - EMB agar](https://i.ytimg.com/vi/_Tn_gPOzjoY/default.jpg)
![Triple Sugar Iron Agar Test](https://i.ytimg.com/vi/XrZqRgbZ1oY/default.jpg)
![Biochemical Tests for Bacterial Identification (Part-1)_TSI, MIU, MR-VP, Lysin, Urea, Citrate](https://i.ytimg.com/vi/afpSDDvdGMc/default.jpg)
![Principle of Salt Mannitol Agar-Isolation of S.aureus (Staphylococcus isolation)](https://i.ytimg.com/vi/vhS8lRwI6CE/default.jpg)
![MacConkey Agar](https://i.ytimg.com/vi/0hwSPTn7JCk/default.jpg)
![Microbiology: Oxidase Test](https://i.ytimg.com/vi/Bv_eNqor_mg/default.jpg)
![MacConkey Agar](https://i.ytimg.com/vi/f0pgH7adv7A/default.jpg)
![Blood smear and Giemsa stain](https://i.ytimg.com/vi/uVaYuq6Jzk4/default.jpg)
![Microbiology lecture 8 | bacterial identification methods in the microbiology laboratory](https://i.ytimg.com/vi/cMVyrrdgaYk/default.jpg)
![Microbiology lecture 2 | Gram positive and Gram negative bacteria Gram staining principle](https://i.ytimg.com/vi/ROqbhi8s3OY/default.jpg)
![Triple Sugar Iron (TSI) Agar](https://i.ytimg.com/vi/gfZ6jothoRc/default.jpg)
![Enterobacteriaceae Family 🦠 شرح بالعربي](https://i.ytimg.com/vi/pSxb0QqqBbo/default.jpg)
![Microbiology: GPC, GNC, GNCB Colonial Growth on BAP & CHOC](https://i.ytimg.com/vi/AWWyNDwkn1U/default.jpg)
![Speciation- Allopatric, Sympatric, Parapatric, Petripatric II Types of Speciation](https://i.ytimg.com/vi/7TNN-WGYWks/default.jpg)
![Gram staining for differentiating bacterial species](https://i.ytimg.com/vi/OOFJyw0EYBU/default.jpg)
![Non-autoclavable media | XLD agar | selective media | Xylose Lysine deoxycholate agar in English](https://i.ytimg.com/vi/5hRy1_YtL1U/default.jpg)
![MacConkey Agar Composition, function of ingredients, uses, and importance explained in Urdu-Hindi](https://i.ytimg.com/vi/R5e_TgDpo90/default.jpg)