Potato dextrose agar
Encyclopedia
Growth medium
A growth medium or culture medium is a liquid or gel designed to support the growth of microorganisms or cells, or small plants like the moss Physcomitrella patens.There are different types of media for growing different types of cells....
made from potato
Potato
The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...
infusion
Infusion
An infusion is the outcome of steeping plants with desired chemical compounds or flavors in water or oil.-History:The first recorded use of essential oils was in the 10th or 11th century by the Persian polymath Avicenna, possibly in The Canon of Medicine.-Preparation techniques:An infusion is very...
, and dextrose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
. Potato dextrose agar (abbreviated "PDA") is the most widely used medium for growing fungi and bacteria which attack living plants or decaying dead plant matter.
Potato infusion can be made by boiling 300 grams (10.6 oz) of sliced (washed but unpeeled) potatoes in water for 30 minutes and then decanting
Decantation
Decantation is a process for the separation of mixtures. This is achieved by carefully pouring a solution from a container in order to leave the precipitate in the bottom of the original container...
or straining the broth through cheesecloth
Cheesecloth
Cheesecloth is a loosewoven gauze-like cotton cloth used primarily in cheese making and cooking.Cheesecloth is available in at least seven different grades, from open to extra-fine weave. Grades are distinguished by the number of threads per inch in each direction.- Uses :The primary use of...
. Distilled water
Distilled water
Distilled water is water that has many of its impurities removed through distillation. Distillation involves boiling the water and then condensing the steam into a clean container.-History:...
is added such that the total volume of the suspension is 1 litres (2.1 US pt). 20 gram (0.705479242102239 oz) dextrose and 20 gram (0.705479242102239 oz) agar powder is then added and the medium is sterilized by autoclaving at 15 pound per square inches (103,421.4 Pa) for 15 minutes.
A similar growth medium, Potato dextrose broth (abbreviated "PDB") is formulated identically to PDA, omitting the agar
Agar
Agar or agar-agar is a gelatinous substance derived from a polysaccharide that accumulates in the cell walls of agarophyte red algae. Throughout history into modern times, agar has been chiefly used as an ingredient in desserts throughout Asia and also as a solid substrate to contain culture medium...
. Common organisms that can be cultured on PDB are yeasts such as Candida albicans
Candida albicans
Candida albicans is a diploid fungus that grows both as yeast and filamentous cells and a causal agent of opportunistic oral and genital infections in humans. Systemic fungal infections including those by C...
and Saccharomyces cerevisiae
Saccharomyces cerevisiae
Saccharomyces cerevisiae is a species of yeast. It is perhaps the most useful yeast, having been instrumental to baking and brewing since ancient times. It is believed that it was originally isolated from the skin of grapes...
and molds such as Aspergillus niger
Aspergillus niger
Aspergillus niger is a fungus and one of the most common species of the genus Aspergillus. It causes a disease called black mold on certain fruits and vegetables such as grapes, onions, and peanuts, and is a common contaminant of food...
.
Further reading
- Atlas, R.M.: Handbook of Microbiological Media, second edition. Lawrence C. Parks (1997)