Önöz agar

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The Önöz agar is a selective medium for the isolation and cultivation of Salmonella and other Enterobacteriacaen. The culture medium meets the criteria of the German Society for Hygiene and Microbiology ( DGHM ).

composition

  • Yeast extract 3.0 g / L
  • Meat extract 6.0 g / L
  • Peptone 6.8 g / L
  • Lactose 11.5 g / L
  • Sucrose 13.0 g / L
  • Bile salts No. 33,825 trisodium citrate 9.3 g / L
  • Sodium thiosulphate 4.25 g / L
  • L-phenylalanine 5.0 g / L
  • Iron (III) ammonium citrate 0.5 g / L
  • Magnesium sulfate 0.4 g / L
  • Brilliant green 0.00166 g / L
  • Neutral red 0.022 g / L
  • Aniline blue 0.25 g / L
  • Metachrome yellow 0.47 g / L
  • Disodium hydrogen phosphate 1.0 g / L
  • Agar 12.0 g / L

pH value adjusted to 7.0 ± 0.2 (after)

cultivation

Cultivation is aerobically for 16 to 24 (48) hours at 35-37 ° C.

properties

Salmonella grow very well as yellow colonies with a black center ( iron sulfide ) and a yellowish halo. Shigella initially grow in the color of the culture medium, later slightly bluish. Escherichia coli grows inhibited (due to the high citrate content of the nutrient medium) as a small blue colony with a rust-colored precipitation zone. Proteus mirabilis shows good growth without swarming phenomenon , rust-colored (due to phenylalanine deaminase) colonies with a black center and a brownish halo . Also Prividencia spp. and Morganella morganii show rust-colored growth. Citrobacter freundii grows well as a pink colony with a green center. Klebsiella and Enterobacter spp. grow as mostly bluish large slimy colonies. Pseudomonads show dirty yellow to greenish growth. Gram-positive bacteria are almost completely inhibited in their growth by bile salts and metachrome yellow.

Further identification

A further serological test can be connected, the O and H antigens of Salmonella are well developed. Further identification takes place according to §35 LMBG or according to the identification tables given under Galle-Chrysoidin-Glycerol-Agar.

swell

  1. ↑ Önöz nutrient medium according to the recommendations of the German Society for Hygiene and Microbiology, accessed on November 24, 2019

literature

  • E. Önöz, K. Hoffmann (1978): Experiences with a new nutrient medium for Salmonella diagnostics . In: Zentralblatt für Bakteriologie, Parasitenkunde, Infektkrankheiten und Hygiene , Dept. I, Originals, Series A, Vol. 240, 1978, pp. 16-21, ISSN  0300-9688 .
  • German Society for Hygiene and Microbiology: DGHM procedural guidelines for microbiological diagnostics . Loose-leaf edition, Fischer-Verlag, Stuttgart, New York 1983, chap. 2.1, ISSN  0720-9940 .