XLD琼脂（根据统一EP/USP/JP）

XLD Agar (Xylose Lysine Deoxycholate Agar) is a selective and differential medium used for isolating and differentiating pathogenic Enterobacteriaceae, particularly Salmonella and Shigella species. The media consists of yeast extract for vitamins, peptic digest of animal tissue for nitrogenous compounds, and agar as a solidifying agent. Xylose, lactose, and sucrose serve as fermentable carbohydrates. L(+)-lysine detects lysine-decarboxylase activity, causing alkalization and a red-violet color. Sodium thiosulfate and ferric ammonium citrate react with hydrogen sulfide to form black iron sulfide precipitates in colonies. Sodium deoxycholate inhibits coliform bacteria, ensuring selectivity.

XLD Agar has diverse applications across industries. In the food and beverage sector, it is used to detect Salmonella and Shigella in meat, dairy, and processed foods, ensuring compliance with safety standards. In water quality testing, it identifies pathogenic Enterobacteriaceae to ensure the safety of drinking water. The pharmaceutical industry employs XLD Agar for microbial testing to detect contamination in products, adhering to pharmacopeial standards.

外观（澄清度）：澄清
外观（颜色）：红色
pH值（25 °C）：7.2 - 7.6
典型成分（g/L）：酵母提取物3.0；氯化钠5.0；D（+）-木糖3.5；乳糖7.5；蔗糖7.5；L（+）-赖氨酸5.0；脱氧胆酸钠2.5；硫代硫酸钠6.8；柠檬酸铵（III）0.8；酚红0.08；琼脂-琼脂13.5。
根据EP、USP和JP协调方法进行促生长试验。
参考培养基上的接种物（鼠伤寒沙门氏菌ATCC 14028（WDCM 00031））：10 - 100
参考培养基上的接种物（阿博尼沙门氏菌 NCTC 6017）：10 - 100
菌落计数（鼠伤寒沙门氏菌 ATCC 14028（WDCM 00031））：
菌落计数（阿博尼沙门氏菌 NCTC 6017）：
在测试培养基上回收率（沙克鼠伤寒沙门氏菌 ATCC 14028（WDCM 00031））： ≥ 50 %
在测试培养基上回收率（阿博尼沙门氏菌 NCTC 6017）： ≥ 50%
菌落颜色（鼠伤寒沙门氏菌ATCC 14028（WDCM 00031））：红色
菌落颜色（阿博尼沙门氏菌NCTC 6017）：红色
黑色中心（鼠伤寒沙门氏菌ATCC 14028（WDCM 00031））：+
黑色中心（阿博尼沙门氏菌NCTC 6017）：+
生长（大肠埃希菌ATCC 8739（WDCM 00012））：无至非常好
菌落颜色（大肠埃希菌ATCC 8739（WDCM 00012））：黄色
培养基颜色（大肠埃希菌ATCC 8739（WDCM 00012））：黄色
沉淀（大肠埃希菌ATCC 8739（WDCM 00012））：+
孵育：沙门氏菌18 hrs.；30-35°C；大肠埃希菌高达48 hrs
以上信息在发布之时为最新信息，如有更改，恕不另行通知（与我们公司签订管理权变更协议的客户除外）。如果公司内部事务或《标准法规》提出要求，则可以随时以任何方式更改信息/格式。

我们现提供两种类型的培养基：GranuCult^®优质颗粒状培养基和NutriSelect^®高性价比粉末状培养基，满足用户不同层次的需求。
商标后的品级称号basic（基础）、plus（加强）或prime（特级）代表产品的不同质控水平，从基础的质控到标准质控加强版到全面合规的特级质控水平。

Typical colonies of Salmonella exhibit a black center surrounded by a translucent red zone due to indicator color changes. H₂S-negative Salmonella, such as Salmonella paratyphi A, grow as pink colonies with a dark pink center. The degradation of xylose results in acidification, causing the medium to turn yellow. Strains with lysine-decarboxylase activity convert L(+)-lysine into cadaverine, causing alkalization and a red-violet coloration of the medium. This activity neutralizes the acids produced during xylose degradation, resulting in a red-violet medium. Lactose and sucrose are added to differentiate lysine-decarboxylase-positive coliform bacteria from Salmonella, as their acid formation cannot be neutralized by cadaverine, leaving the medium yellow. Deoxycholate inhibits coliform bacteria growth, while thiosulfate and iron (III) salt react with hydrogen sulfide to form black iron sulfide precipitates in colonies. Sodium thiosulfate is reduced by Salmonella and other sulfate-reducing bacteria to H₂S, which reduces ferric ammonium citrate to black iron sulfide. This reaction is more pronounced under alkaline conditions, but H₂S-producing bacteria that form acids from lactose or sucrose, such as Citrobacter spp. and Proteus spp., may show weaker black centers. Salmonella typhi colonies often appear yellow-orange or pink.

GRANUCULT is a registered trademark of Merck KGaA, Darmstadt, Germany

NutriSelect is a registered trademark of Merck KGaA, Darmstadt, Germany