革兰氏阴性菌






Gram-negative 革兰氏阴性铜绿菌（粉紅色棒状）


革兰氏阴性菌（Gram-negative），革兰氏阴性菌泛指革兰氏染色反应呈红色的细菌。在革兰氏染色实验中，首先添加了結晶紫，再添入另一种复染染料（通常使用番红（safranin）），从而将所有的革兰氏阴性菌染成红色或粉色。通过这种测试我们可以区分两种细胞壁结构不同的细菌。[1]革兰氏阳性菌在反应后的除色溶液中将呈现龙胆紫的颜色。相較於革蘭氏陽性菌，陰性菌通常會導致人類疾病——例如最具代表性的大腸桿菌。


革兰氏阴性菌细胞壁中肽聚糖含量低，而脂类含量高。当用乙醇处理时，脂类物质溶解，细胞壁通透性增强，使結晶紫极易被乙醇抽出而脱色；再度染上复染液番红的时候，便呈现红色了。


革兰氏阴性菌的病原能力通常与其细胞壁组成相关，具体说来有脂多糖层。在人体中，LPS可以激发一种先天免疫系統这种反应是通过细胞素制造和免疫系统活化等来描述其特征的。比如，红肿就是细胞素产生并释放导致的。因為脂多糖在革蘭氏陰性菌的細胞牆表皮，所以大多數或舊型抗生素都不能有效抑制此類細菌。




目录






  • 1 特征


  • 2 参考文献


  • 3 参见


  • 4 外部連結





特征




Gram-negative 革兰氏阴性菌的结构




Gram-negative 革兰氏阴性菌与革兰氏阳性菌结构对比


以下为革兰氏阴性菌的特征：




  1. 细胞膜：存在于细胞质中各膜结合细胞器中的膜，包括核膜、内质网膜、高尔基体膜、溶酶体膜、线粒体膜、叶绿体膜、过氧化物酶体膜等。

  2. 肽聚糖薄层，比革兰氏阳性菌要薄得多


  3. 外层膜（outer membrane），是在肽聚糖层之外的膜，内含有脂多糖，核糖，O抗原

  4. 外层膜中还有孔蛋白，允许特定的分子通过

  5. 周质（periplasmic space）： 指肽聚糖层和外层膜之间的空间

  6. S层直接与外层膜相连，而非肽聚糖层

  7. 如果有鞭毛，表毛有四个支撑环而不是两个

  8. 没有磷壁酸或者脂磷壁酸

  9. 多糖骨架上有脂蛋白

  10. 大多数革兰氏阴性菌中含有胞壁质脂蛋白（Braun's lipoprotein），其作用为通过共价键连接外层膜和多糖

  11. 绝大多数革兰氏阴性菌非孢子生殖，除了极少数例外（伯氏考克斯体（Coxiella burnetii）除外）

  12. 一些革兰氏阴性菌释放脂多糖



参考文献





  1. ^ Baron S, Salton MRJ, Kim KS. Structure. (编) Baron S; 等. Baron's Medical Microbiology 4th. Univ of Texas Medical Branch. 1996. ISBN 0-9631172-1-1. PMID 21413343.  引文格式1维护：显式使用等标签 (link)




参见



  • 细菌

  • 革蘭氏染色

  • 革蘭氏陽性菌

  • 非维管植物

  • 敗血症



外部連結


  • 革蘭氏陰性菌(Gram-negative bacteria)



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