Capsule stain (莢膜染色) Capsule is an extra-cellular structure to protect bacteria from environmental stress or immunological response inside host. Generally, bacteria with capsule possess pathogenicity. Chapter 14, page 83
目的 莢膜為細菌所分泌帶有黏性之物質，主要附著於細菌之細胞壁並圍繞於菌體周圍，但並非所有的細菌均可產生莢膜。具有莢膜之細菌，於宿主體內具有可保護吞噬作用，故含有厚層莢膜之細菌被視為具有毒力且易引起疾病。以化學組成而言，莢膜物質大多為多醣類、醣蛋白或聚胜肽，另外，莢膜係可溶性物質，故可因激烈沖洗而流失或脫離，因此莢膜染色法較其他各種鑑別染色法更為困難。本實驗旨在讓學生瞭解莢膜染色之原理並學習細菌的莢膜染色法，以明白菌體之構形。
原理 由於莢膜與染料間的親合力弱，不易著色。通常會採用負染色法即讓菌體和背景著色，而莢膜不染色，而使莢膜在菌體周圍呈一透明圈。由於莢膜的含水量在90%以上，故染色時一般不加熱固定，以免莢膜皺縮變化。
材料與儀器 菌種 試劑 設備儀器及其他用具
菌種 Medium: Stain Equipments Escherichia coli Bacillus subtilis Klebsiella pneumoniae Medium: nutrient agar (NA) or tryptic soy agar (TSA). Stain Congo red Congo red mordant Equipments microscope
Klebsiella pneumoniae The Danish scientist Hans Christian Gram (1853–1938), developed the technique now known as Gram staining in 1884 to discriminate between K. pneumoniae and Streptococcus pneumoniae. Klebsiella was named after the German bacteriologist Edwin Klebs (1834–1913). (屬腸內細菌科，Enterobacteriaceae)。 Klebsiella pneumonia is a form of bacterial pneumonia associated with Klebsiella pneumoniae. It is typically due to aspiration by alcoholics, though it is more commonly implicated in hospital-acquired urinary tract and wound infections, particularly in immunocompromised individuals and diabetics. (opportunity pathogen; 機會感染菌)。
設備儀器及其他用具 酒精燈（或本生燈） 接種環（或接種針） 染色架 濾紙 拭鏡紙 玻片 顯微鏡
Dye (page 301) Congo red Congo red mordant 1% 5% Phenol 20% acetic acid 30% ferric chloride 1% fuchsion acid
步驟與方法 染色方法之操作流程如下：
Take one colony on a plate, spread on slide . Add Congo red and mordant on the bacterial spread. You can add the Congo red and mordant on the glass slide first, then take a bacterial colony, and spread the colony in the dye. Air dry. DO NOT use flame. (不可用火)。 Stain for 90 sec. Use water to remove excess stain. Observe under microscope.