GSP Agar

EMD Cat. No. 1.10230.0500
500 g


Medium proposed by KIELWEIN (1969, 1971) for detecting Pseudomonas and Aeromonas in foodstuffs as well as in wastewater and equipment of the food industry.



Additives


EMD Cat. No. Product Pack Size
1.06993.0010 Penicillin G potassium salt
EMD Biosciences Pimaricin 1 g



Mode of Action Preparation
Experimental Procedure and Evaluation Quality Control
Typical Composition (g/liter) Literature
Picture/Image


Mode of Action
 This glutamate starch phenol-red agar contains glutamate and starch as its sole nutrients. Many accompanying microorganisms cannot metabolize these compounds (STANIER et al. 1966). Starch is degraded by Aeromonas with acid production causing phenol red to change the yellow, but not by Pseudomonas. The selective inhibitors penicillin and, if desired, the antimycotic pimaricin are added to the medium to improve its selectivity.
Preparation
Suspend 45 g/liter, autoclave (15 min at 121 °C), cool to
45-50 °C. Add 100,000 IU sodium penicillin g/liter and, if required, 0.01 g pimaricin/liter, mix and pour plates.
 pH: 7.2 ± 0.2 at 25 °C.
 The plates are clear and red.
Experimental Procedure and Evaluation
 Inoculate by spreading the sample material on the surface of the plates.
 Incubation: up to 3 days at approx. 28 °C aerobically.
Appearance of Colonies
 		Microorganisms
Large, diameter of 2-3 mm, blue-violet, surrounded by a red-violet zone
 		Pseudomonas
Large, diameter of 2-3 mm, yellow, surrounded by a yellow zone
 		Aeromonas
Usually small, delayed growth, sometimes mucoid
 		Enterobacteriaceae and others

Quality control

Test strains
 Growth
 		color change to
Pseudomonas aeruginosa ATCC 27853
 		good / very good
 		red-violet
Pseudomonas aeruginosa ATCC 9027
 		good / very good
 		red-violet
Pseudomonas aeruginosa ATCC 10145
 		fair / good
 		red-violet
Aeromonas hydrophila ATCC 7966
 		good / very good
 		yellow
Aeromonas caviae ATCC 15467
 		good / very good
 		yellow
Escherichia coli. ATCC 25922
 		none / poor
 		-
Staphylococcus aureus ATCC 25923
 		none

Typical Composition (g/liter)
 Sodium L(+)glutamate 10.0; starch, soluble 20.0; potassium dihydrogen phosphate 2.0; magnesium sulfate 0.5; phenol red 0.36; agar-agar 12.0
 Also to be added:
 penicillin G 100,000 IU; if required pimaricin 0.01.
Literature

KIELWEIN, G., GERLACH, R., u. JOHNE, H.: Untersuchungen über das Vorkommen von Aeromonas hydrophila in Rohmilch. - Arch. f. Lebensmittelhyg., 20; 34-38 (1969).
 KIELWEIN, G.: Ein Nährboden zur selektiven Züchtung von Pseudomonaden und Aeromonaden. - Arch. f. Lebensmittelhyg., 20; 131-133 (1969).
 KIELWEIN, G.:Pseudomonaden und Aromonaden in Trinkmilch: Ihr Nachweis und ihre Bewertung. - Arch. f. Lebensmittelhyg., 22; 15-19 (1971).
 KIELWEIN, G.: die Isolierung und Differenzierung von Pseudomonaden aus Lebensmitteln. - Arch. f. Lebensmittelhyg., 22; 29-37 (1971).
 STANIER, R.Y., PALLERONI, N.J., a. DOUDOROFF, M.: The aerobic Pseudomonas - a taxonomic study. - J. Gen. Microbiol., 42; 159-271 (1966).


Pseudomonas aeruginosa



© 2002 Merck KGaA, Darmstadt, Germany