Gram-positive and Gram-negative Bacteria革兰阳性菌和革兰阴性菌
"Bacteria are classified by gram staining. This is a process that determines many things - resistance to antibiotics, for one thing. It is also one of the first things scientists will do when trying to identify an unknown bacteria. It involves staining a group of bacteria with four different liquids. First, crystal violet is added. Then it's stained with iodine, and finally with safranin. Then it goes through an alcohol wash. The bacteria that retain the purple stain from the crystal violet are gram-positive, and those that take on the pink stain from the safranin are gram-negative."
"This has to do with the outer layer of the cell - gram positive bacteria have a thick layer of peptidoglycan, which absorbs the gram stain. Gram-negative bacteria have a thick lipid bilayer on the outside, which is selectively permeable - not everything can pass through it, and one of those things is the gram stain. The gram-positive bacteria (since things can pass through it easily) are much more susceptible to antibiotics than gram-negative bacteria." 这与细胞的外层有关——革兰氏阳性菌具有厚层的肽聚糖，可以吸收革兰氏染色。革兰氏阴性菌则在外层有厚的脂双层，具有选择透过性——并非所有物质都能通过它，其中一种就是革兰氏染色。由于物质可以较容易地通过，革兰氏阳性菌比革兰氏阴性菌更容易受到抗生素的影响。
细菌根据格兰染色法进行分类。这一过程可以确定许多特性，例如对抗生素的抗性。这也是科学家在尝试鉴定未知细菌时首先进行的步骤之一。该过程涉及用四种不同的液体对一组细菌进行染色。首先，加入结晶紫。然后用碘液染色，最后用沙黄染色。之后进行酒精冲洗。保留结晶紫染色的紫色细菌属于格兰阳性菌，而被沙黄染色呈粉色的细菌则属于格兰阴性菌。 |
Index Reference Enger & Ross 索引参考Enger & Ross | ||
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