Agar Medium for Differential Enumeration of Lactic Streptococci

[所属分类:培养基配方] [发布时间:2019-9-23] [发布人:] [阅读次数:] [返回]

山东拓普生物工程有限公司

Shandong Tuopu Biol-Engineering Co.,Ltd

Agar Medium for Differential
Enumeration of Lactic Streptococci
Composition per 1170.0mL:
Agar ............................................................................................15.0g
Carboxymethylcellulose .............................................................15.0g
Calcium citrate............................................................................10.0g
Pancreatic digest of casein............................................................5.0g
Yeast extract..................................................................................5.0g
L- Arginine·HCl..............................................................................5.0g
Casamino acids.............................................................................2.5g
K 2 HPO 4 .......................................................................................1.25g
Calcium carbonate solution ...................................................100.0mL
Nonfat milk solution................................................................50.0mL
Bromcresol Purple solution .....................................................20.0mL
pH 5.9 ± 0.2 at 25°C
Calcium Carbonate Solution:
Composition per 100.0mL:
CaCO 3 ...........................................................................................3.0g
Preparation of Calcium Carbonate Solution: Add CaCO 3 to
distilled/deionized water and bring volume to 100.0mL. Mix thorough-
ly. Autoclave for 15 min at 15 psi pressure–121°C.
Nonfat Milk Solution:
Composition per 100.0mL:
Nonfat milk................................................................................. 11.0g
Preparation of Nonfat Milk Solution: Add nonfat milk to dis-
tilled/deionized water and bring volume to 100.0mL. Mix thoroughly.
Autoclave for 15 min at 15 psi pressure–121°C.
Bromcresol Purple Solution:
Composition per 20.0mL:
Bromcresol Purple......................................................................0.02g
Preparation of Bromcresol Purple Solution: Add Bromcresol
Purple to distilled/deionized water and bring volume to 20.0mL. Mix
thoroughly. Filter sterilize.
Preparation of Medium: Add agar to 500.0mL of distilled/deion-
ized water. Gently heat and bring to boiling. In a separate flask, add
carboxymethylcellulose and calcium citrate to 500.0mL of distilled/de-
ionized water. Gently heat while stirring until a white, turbid suspen-
sion is formed. Combine the two solutions. Add the pancreatic digest
of casein, yeast extract, K 2 HPO 4 , casamino acids, and arginine. Mix
thoroughly. Gently heat and bring to boiling. Adjust pH to 5.6 with 6N
HCl. Distribute into screw-capped bottles in 100.0mL volumes. Auto-
clave for 15 min at 15 psi pressure–121°C. Cool to 45°–50°C. Imme-
diately prior to pouring plates, aseptically add 5.0mL of sterile nonfat
milk solution, 10.0mL of sterile calcium carbonate solution, and 2.0mL
of sterile Bromcresol Purple solution to each screw-capped bottle. Mix
thoroughly. The pH should be 5.9. Pour into cold, sterile Petri dishes.
Use: For the cultivation, differentiation, and enumeration of Lactoba-
cillus lactis, Lactobacillus lactis subspecies cremoris, and Lactobacil-
lus lactis subspecies diacetylactis. Lactose-fermenting bacteria such as
Lactobacillus lactis subspecies cremoris appear as yellow colonies.
Arginine-utilizing bacteria such as Lactobacillus lactis and Lactobacil-
lus lactis subspecies diacetylactis appear as purple colonies. Citrate-
utilizing bacteria such as Lactobacillus lactis subspecies diacetylactis
appear as colonies surrounded by a clear zone.