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1、实验一 细菌的革兰氏染色,一 教学要求 了解不同的细菌染色方法的原理，掌握革兰氏染色方法的操作技术。二 实验原理1、染色方法Since bacteria are almost colorless and therefore show little contrast with the broth in which they are suspended,they are difficult to observe when unstained.Staining microorganisms enables one to:-see greater contrast between the organi
2、sm and the background,differentiate various morphological types(by shape,arrangement,gram reaction,etc.),-observe certain structures(flagella,capsules,endospores,etc.),Simple stainsSimple stains highlight the organism so basic structures are visible in microscope.Differential stainsDifferential stai
3、ns react differently with different kinds of bacteria.Special stains Used to color and isolate various structures,such as capsules,endospores,and flagella.,Simple stains,2、革兰氏染色,Gram Stain-developed Christian Gram in 1884The gram stain is the most widely used staining procedure in bacteriology.It is
4、 called a differential stain since it differentiates between gram-positive and gram-negative bacteria.Bacteria which stain purple with the gram staining procedure are termed gram-positive;those which stain pink are said to be gram-negative.Gram-positive and gram-negative bacteria stain differently b
5、ecause of fundamental differences in the structure of their cell walls.,Structure of a Gram-Negative Cell Wall Structure of a Gram-Positive Cell Wall,三 材料与器材,菌种：大肠杆菌约24 h营养琼脂斜面培养物，金黄色葡萄球菌约24 h 营养琼脂斜面培养物。革兰氏染色液载玻片、酒精灯、显微镜。,四 操作步骤,制片（涂片，干燥，固定）初染（草酸铵结晶紫染1 min，水洗）媒染（加碘液覆盖涂面染1 min，水洗，用吸水纸吸去水分）脱色（加95%酒精数滴，并轻轻摇动进行脱色，20 s后水洗，用吸水纸吸去水分）复染（蕃红复染约1 min，水洗）干燥镜检,Smear preparation,Staining,Heat fixing,crystal violet stain wash with water,Stain with grams iodine solution,Decolorize by adding 95%alcohol,Counterstain with Safranin,五 注意事项注意涂片不宜过。火焰固定温度要适宜。注意控制好脱色程度。六 思考题造成革兰氏染色结果不正确（假阴性或假阳性）的主要原因有哪些？,
