Understand the Spiderman of the Microverse: XLD Agar
Learning XLD’s X, Y, and Z can be challenging, but not with us. In the previous article, we discussed the various needs and applications of XLD (click on the link if you haven’t read it). In this, we’ll talk more about its composition, principle, observations, and modifications.
What is the composition of XLD Agar?
It was developed by Welton Taylor in 1965. XLD stands for Xylose Lysine Deoxycholate Agar and is a bright pink or red-colored solid opalescent gel medium. Knowing its key contents will help you better understand its principles and differentiating abilities.
Ferric Ammonium Citrate 0.8 g
Yeast extract provides the medium with nutrients, vitamins, peptides, and other essential growth factors. Xylose, lactose, and sucrose are rich sources of fermentable carbohydrates. For the detection of fermentation of these carbs in the medium, a pH indicator, phenol red, is added. The addition of xylose to the medium accounts for the differentiation of various fermenting enteric bacteria from species of Shigella that do not ferment it. Most enteric pathogens, including Salmonella,can ferment xylose, which results in the formation of acidic byproducts and a change in the color of the medium from pink to yellow, whereas Shigella colonies remain red. In some cases, Salmonella imitates Shigella colonies and gives red colonies, which are then differentiated by the production of Hydrogen sulfide gas by the metabolism of thiosulfate and give black centers. Enterobacteria such as E. coli can ferment lactose in the medium.
XLD Agar’s composition can be adjusted according to one’s needs and choices and is hence available in many different variations, but the basic principle remains the same.
Observation and Inferences on XLD Agar:
Red colonies, some with black centers Salmonella spp.
Red colonies Shigella spp.
Yellow to orange colonies Coliforms
Pink, flat, and rough colonies Pseudomonas aeruginosa
While learning about XLD Agar, a question that must have run through your thoughts would’ve been, “Where is XLD Agar available?” Let’s look into it.
Where is XLD Agar available?
XLD Agar is available on the market as Dehydrated Culture Media in a number of variations according to one’s requirements, including plant-based and animal-based options.
These Dehydrated Culture Media can be dissolved in distilled water according to the concentration mentioned on the package, autoclaved, poured, and used.
TM Media, the microbiology division of Titan Biotech Ltd., offers a wide range of XLD Agar as Dehydrated Culture Media in a number of variations suitable for all your needs, operations, and specific requirements.
The product range includes the following:
XLD AGAR MODIFIED (as per ISO) TM 1621: XLD Agar, modified, is a selective and differential medium for the isolation of gram-negative enteric pathogens from clinical specimens or food products. It is a modification of the original formulation of Taylor that allows selective isolation of Salmonella typhi, E. coli, Salmonella enteritidis, Salmonella typhimurium, and Shigella flexneri. It is recommended by the ISO committee, and the composition and performance criteria of this medium are as per the specifications laid down in ISO 6579-1:2017.
XLD AGAR (VEG.) TMV 492: Xylose Lysine Deoxycholate Agar (Veg) is prepared by replacing Sodium Deoxycholate with synthetic detergent No.III, which makes the medium free of BSE/TSE risks. Xylose Lysine Deoxycholate Agar (Veg) is suitable for the isolation and identification of enteric pathogens from stool samples.
XLD AGAR (as per USP/EP/JP/BP) TMH 112: This medium is employed for pharmaceutical testing and non-sterile product testing for the detection of Salmonella after enrichment in Rappaport VassialidiasSalmonella Enrichment Broth in accordance with the harmonized method of USP/EP/BP/JP/IP.
XLD AGAR TM 1448: It is used for pharmaceutical testing and nonsterile product testing for the detection (or absence) of Salmonella after enrichment in Rappaport Vassialidias Salmonella Enrichment Broth in accordance with IP.
XLD AGAR TM 492: XLD Agar exhibits increased selectivity and sensitivity as compared to other plating media, e.g., SS Agar, EMB Agar, and Bismuth Sulphite Agar. The media formulation does not allow the overgrowth of other organisms over Salmonella and Shigella. Samples suspected of containing enteric pathogens, along with other mixed flora, are initially enriched in Modified Semisolid RV Medium Base.
Why choose TM Media’s XLD Agar?
TM Media’s superior-quality and diverse Microbiological Culture Media are certified by ISO, CE, GMP, FSSAI, and FSSC.
TM Media provides unrivaled convenience, dependability, and efficacy, as well as versatility and flexibility, by manufacturing a contamination-free medium with a longer shelf life and reproducible outcomes.
XLD Agar is a selective and differential agar medium primarily used for the isolation and differentiation of different enteropathogenic organisms that are well-known to cause diseases like Food poisoning, Gastroenteritis, and other Digestive illnesses.
By choosing TM Media, consumers invest in precision, quality, and excellence. TM Media's product portfolio includes over 2000 Dehydrated Culture Media, along with Ready-to-Use Culture Media, Biological Media Bases, Media Supplements, Lab Chemicals, and many more.
