微生物檢測培養基的配方及原理
發布時間：
2022-11-16
作者：
1 月桂基硫酸鹽胰蛋白胨肉湯(LST)
原 理：
月桂基硫酸鈉，別名月桂醇硫酸鈉，表面活性作用強，具有乳化作用。
一種優質蛋白胨，是以新鮮牛肉和牛骨經胰酶消化，濃縮干燥而成的淺黃色粉末。具有色淺、易溶、透明、無沉淀等良好的物理性狀。含有豐富的氮源、氨基酸等胰蛋白胨或胰酪胨 20g 提供碳源和氮源滿足細菌生長的需求 。
配方（g/L）
2 煌綠乳糖膽鹽(BGLB)肉湯（Brilliant Green Lactose Bile Broth）
原理：
膽鹽（Bile Salt）：是一種膽酸的鈉鹽，是膽酸的羧基和甘氨酸或牛磺酸(C2H7NO3S)的氨基(C2H5NO2)，通過酰胺鍵結合而成。
① 可降低培養基與細菌細胞膜界面上的表面張力，使細胞膜紊亂，導致細菌自溶。
②腸桿菌科細菌在腸道內長期與膽汁接觸。對膽鹽有一定的抵抗力。合適的膽鹽量能促進該科細菌的生長。
③膽鹽遇酸生成沉淀，使菌落色素不致擴散從而有利于鑒別。
④膽鹽中含有一定量的膽紅素、粘蛋白、色氨酸，對不受膽鹽抑制的細菌生長有營養作用。
煌綠（亮綠）：抑制革蘭氏陽性菌和大多數非沙門氏菌的革蘭氏陰性桿菌，通常抑制發酵乳糖、蔗糖的細菌。煌綠和枸櫞酸鈉對大腸菌的生長、菌體蛋白質的合成和糖的利用都有顯著的抑制作用，以煌綠的作用為較強。枸酸鈉能抑制大腸菌的呼吸，而煌綠的抑制作用則較弱。混合膽鹽及硫代硫酸鈉對大腸菌的上述代謝活動都沒有抑制作用。
配方：（g/L）
用法：
將蛋白胨、乳糖溶于約500 ml蒸餾水中，加入牛膽粉溶液200 ml（將20.0 g 脫水牛膽粉溶于200 ml 蒸餾水中，調節pH至7.0～7.5），用蒸餾水稀釋到975 ml，調節pH，再加入0.1%煌綠水溶液13.3 ml， 用蒸餾水補足到1000 ml，用棉花過濾后，分裝到有玻璃小倒管的試管中，每管10ml 。121 ℃高壓滅 15 min 。
3 伊紅美藍瓊脂(EMB)Eosin-Methylene Blue Agar
原理：
伊紅美藍瓊脂含有伊紅和美藍兩種苯胺類染料，它們可以抑制革蘭氏陽性菌的生長。伊紅為酸性染料，美藍為堿性染料。當大腸桿菌分解乳糖產酸時細菌帶正電荷被染成紅色，再與美藍結合形成紫黑色菌落，并帶有綠色金屬光澤。而產氣桿菌則形成呈棕色的大菌落。
在堿性環境中不分解乳糖產酸的細菌不著色，伊紅和美藍不能結合，故沙門氏菌等為無色或琥珀色半透明菌落。金葡菌在此培養基上不生長。
常用的伊紅美藍乳糖培養基，可用來鑒別飲用水和乳制品中是否存在大腸桿菌等細菌。如果有大腸桿菌，因其強烈分解乳糖而產生大量的混合酸，菌體帶H+，故菌落被染成深紫色，從菌落表面的反射光中還可以看到金屬光澤。
配方：（g/L）
用法：
稱取本品 37.4g，加熱攪拌溶解于 1000ml 蒸餾水中，分裝三角瓶，121℃高壓滅菌15分鐘， 備用。
4 EC肉湯 (E.Coli Broth)
用途：
用于糞大腸菌群、大腸桿菌的測定(GB2008、SN標準)。
配方：（g/L）
5 營養瓊脂斜面 營養瓊脂（NA）Nutrient Agar
用途：
細菌計數、不含糖，可作血瓊脂基礎和傳代用(GB標準)。
配方：（g/L）
1 lauryl sulfate tryptone broth (LST)
The original reason:
Sodium lauryl sulfate, also known as sodium lauryl sulfate, has strong surface activity and emulsifying effect.
A high quality pepptone is a light yellow powder made from fresh beef and bovine bone digested by trypsin. It has good physical properties such as light color, soluble, transparent and no precipitation. Rich in nitrogen sources, amino acids and other tryptone or tryptone 20g provide carbon sources and nitrogen sources to meet the needs of bacterial growth.
Formula (g/L)
2. Brilliant Green Lactose Broth (BGLB) Broth
Principle:
Bile Salt: a sodium Salt of Bile acid. It is the carboxyl group of Bile acid and the amino group of glycine or taurine (C2H7NO3S).
The surface tension at the interface between the culture medium and the bacterial cell membrane can be decreased, and the membrane can be disordered, leading to bacterial self-dissolution.
Potassium enterobacteriaceae bacteria are exposed to bile in the intestine for a long time. Have some resistance to gallbladder salt. The proper amount of bile salt can promote the growth of bacteria in this family.
When the gallbladder salt encounters an acid, it forms a precipitate, which prevents the colony pigment from diffusing and thus facilitates identification.
In addition, some amount of bilirubin, mucin and tryptophan are contained in bile salts, which can nourish the growth of bacteria that are not inhibited by bile salts.
Huang green (bright green) : gram-negative bacteria that inhibit gram-positive bacteria and most non-salmonella bacteria, usually those that ferment lactose and sucrose. Chlorophyll and sodium citrate have significant inhibitory effects on the growth of coliform bacteria, the synthesis of protein and the use of sugar. Sodium cotonate can inhibit the respiration of coliform coliforms, while the inhibition of chlorophyll is weak. Mixed bile salts and sodium thiosulphate did not inhibit the above metabolic activities of coliform bacteria.
Formula :(g/L)
Usage:
Be lactose peptone, dissolve in about 500 ml of distilled water, add 200 ml ox-gall powder solution (20.0 g dehydration ox-gall powder in 200 ml of distilled water, adjust the pH to 7.0 ~ 7.5), diluted with distilled water to 975 ml, adjust pH value, add 0.1% 13.3 ml, bright green water solution with distilled water up to 1000 ml, with cotton filter the partial shipments to have a small glass tube of the test tube, 10 ml per tube. 121 ℃ high pressure for 15 min.
EMB. Eosin-methoxide Blue Agar
Principle:
Agar-agar ichenide contains two aniline dyes, ichene and methylene blue, which inhibit the growth of gram-positive bacteria. Iron is an acid dye and methylene blue is an alkaline dye. When escherichia coli breaks down lactose to produce acid, the bacteria are positively charged and dyed red, which then combines with methylene blue to form a purple-black colony with a greenish-metallic sheen. Aerobe forms large brown colonies.
Bacteria that do not decompose lactose and produce acid in alkaline environment do not stain, and irradiation and blue cannot combine, so salmonella is a colorless or amber translucent colony. S. aureus does not grow in this medium.
The commonly used culture medium of erythromycin blue lactose can be used to identify the presence of e. coli and other bacteria in drinking water and dairy products. If there are escherichia coli, because of its strong lactose) and produce a lot of mixed acid, bacteria with H +, so the colonies were dyed purple, from the surface of the colony of reflected light can also be seen in the metallic luster.
Formula :(g/L)
Usage:
Said this product is 37.4 g, heat stirring dissolved in 1000 ml of distilled water, repackaging triangle bottle, 121 ℃ high pressure sterilization for 15 minutes. Set aside.
4. EC Broth (e. coli Broth)
USES:
Used for the determination of fecal coliforms and e. coli (GB2008, SN standards).
Formula :(g/L)
5 nutrient AGAR slant Nutrient Agar (NA) Nutrient Agar
USES:
Bacteria count, no sugar, can be used as blood AGAR foundation and for the generation (GB standard).
Formula :(g/L)
The formula is shown in the figure above.
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