CONGO RED AGAR, A DIFFERENTIAL MEDIUM FOR AEROMONAS-SALMONICIDA, DETECTS THE PRESENCE OF THE CELL-SURFACE PROTEIN ARRAY INVOLVED IN VIRULENCE
CONGO RED AGAR, A DIFFERENTIAL MEDIUM FOR AEROMONAS-SALMONICIDA, DETECTS THE PRESENCE OF THE CELL-SURFACE PROTEIN ARRAY INVOLVED IN VIRULENCE
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DOI：
10.1128/jb.164.3.1233-1237.1985
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发表时间：
1985-01-01
影响因子：
3.2
通讯作者：
KAY, WW
中科院分区：
文献类型：
--
作者：
ISHIGURO, EE;AINSWORTH, T;KAY, WW
鱼类病原体沙门氏菌气单胞菌具有参与毒力的细胞表面蛋白阵列A层（A+），在30 .亩的大豆琼脂上形成深红色菌落。这些很容易与无色或浅橙色的无A层（A-）的无毒突变体菌落区分开来。证实了刚果红琼脂定量测定A+和A-细胞在常规培养毒力评估中的应用。完整的A+细胞吸附刚果红，而A-突变体除非先通过EDTA渗透，否则不能结合刚果红。A+细胞的染色结合组分显示为表面阵列的50,000-Mr A蛋白组分。纯化的a蛋白通过高盐浓度增强的非特异性疏水机制，以染料与蛋白的摩尔比约为30的方式与刚果红紧密结合。在低盐浓度下，A+和A-细胞都不能被刚果红- sepharose吸收。另一方面，在高盐浓度下，A+（而不是A-）细胞被强烈结合。
Strains of the fish pathogen Aeromonas salmonicida which possess the cell surface protein array known as the A-layer (A+) involved in virulence formed deep red colonies on tryptic soy agar containing 30 .mu.g of Congo red per ml. These were readily distinguished from colorless or light orange colonies of avirulent mutants lacking A-layer (A-). The utility of Congo red agar for quantifying A+ and A- cells in the routine assessment of culture virulence was demonstrated. Intact A+ cells adsorbed Congo red, whereas A- mutants did not bind Congo red unless first permeabilized with EDTA. The dye-binding component of A+ cells was shown to be the 50,000-Mr A-protein component of the surface array. Purified A-protein avidly bound Congo red at a dye-to-protein molar ratio of about 30 by a nonspecific hydrophobic mechanism enhanced by high salt concentrations. Neither A+ nor A- cells absorbed to Congo red-Sepharose columns at low salt concentrations. On the other hand, A+ (but not A-) cells were avidly bound at high salt concentrations.