KING FG AGAR
CAT Nº: 1053
For the enumeration of psychotropic microorganisms in foods
FORMULA IN g/l
Bacteriological Peptone
20.00 Potassium Phosphate
1.50
Maltose
10.00 Magnesium Sulfate
0.75
Sodium Chloride
5.00 Bacteriological Agar
15.00
Final pH 7.0 ± 0.2 at 25ºC
PREPARATION
Suspend 52.25 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent
agitation. Boil for one minute until complete dissolution. Sterilize in autoclave at 121ºC for 15 minutes. Cool to 45-50ºC
and aseptically add 2 ml of sterile-filtered 0.05% crystal violet solution. Homogenize gently and dispense into Petri
dishes. The prepared medium should be store at 8-15°C. The color is amber, slightly opalescent.
The dehydrated medium should be homogeneous, free-flowing and beige in color. If there are any physical changes,
discard the medium.
USES
KING FG AGAR is used for the enumeration of psychotropic microorganisms in foods and drinks.
Psychotropic organisms can tolerate low temperatures between 4 – 20°C. Organisms in this group are Pseudomonas,
Achromobacter, Alcaligenes, Flavobacterium, and Aeromonas, as well as other species of enterobacteriaceae from the
genera: Escherichia, Proteus, Klebsiella, Enterobacter and Hafnia. These are all Gram negative bacteria.
Peptone provides provide nitrogen, vitamins, minerals and amino acids essential for growth. Maltose is a fermentable
carbohydrate as an energy and carbon source. Sodium chloride supplies essential electrolytes for transport and osmotic
balance. Potassium phosphate and Magnesium sulfate provide minerals and ions and act as a buffer. Bacteriological agar
is the solidifying agent. Crystal violet inhibits gram-positive bacteria.
The total count per ml of food sample is performed using serial dilutions, placing 1.0 ml of each dilution on the surface
of the medium and spreading it with a sterile glass rod. Incubation should last 5 days at 17°C.
Count only larger (not punctiform) colonies and multiply by the dilution factor to obtain the total count.
MICROBIOLOGICAL TEST
The following results were obtained in the performance of the medium from type cultures, with Crystal violet added,
after incubation at a temperature of 17°C and observed after 4-5 days.
Microorganisms
Pseudomonas spp
E.scherichia coli ATCC 25922
Proteus mirabilis ATCC 14273
Growth
Good
Good
Good
BIBLIOGRAPHY
Pascual Anderson – Metodología analítica para alimentación y bebidas - Diaz Santos, 1999.
1
LABORATORIOS CONDA, S.A.
www.condalab.com
STORAGE
25ºC
Once opened keep powdered medium closed to avoid hydration.
2ºC
2
LABORATORIOS CONDA, S.A.
www.condalab.com