Medio basal para pruebas de oxido-fermentación

TECHNICAL DATA SHEET #585 REV. 2

PRODUCT:

OXIDATIVE-FERMENTATIVE MEDIA (OF BASAL MEDIA)

Tube Media:a OF Basal Medium, Control, Hugh-Leifson, item no. T7140 OF Basal Medium With 1% Specific Carbohydrate, Hugh-Leifson, item no.’s T7142 (dextrose), T7143 (fructose), T7146 (lactose), T7148 (maltose), T7150 (mannitol), T7162 (sucrose), T7156 (xylose) OF Medium, Control, King, item no. T7178OF Medium With 1% Specific Carbohydrate, King, item no.’s T7180 (dextrose), T7186 (lactose), T7188 (maltose), T7191 (mannitol), T7192 (sucrose), T7196 (xylose)
a

see catalog for ordering options

PURPOSE:

OF basal medium is a low peptone-containing medium that detects the acid produced by microorganisms that require oxygen for the degradation of carbohydrates. The utilization of OF GlucoseMedium allows for the categorization of microorganisms as fermenters, oxidizers, or nonoxidizers. In addition, the motility of the microbe can be determined with this semisolid medium.

Hugh and Leifson1,2 first realized that microorganisms utilizing carbohydrates via an aerobic metabolic pathway produced only a minimal amount of acid. In media containing large amounts of peptones, these samemicrobes would utilize the peptones, producing enough alkaline by-products to obscure the acid produced. Hugh and Leifson decreased the ratio of peptone to carbohydrate in the medium to a 0.2:1 ratio which minimized the formation of alkaline by-products; the subsequent increased carbohydrate concentration enhanced the acid production by the microbes.3 The semisolid consistency of the agar preventsdilution of any acid produced, as well as keeping the acid concentrated at the site of production. Bromthymol blue or phenol red acts as an indicator and changes to yellow when acid is formed. The Centers for Disease Control prefers the phenol red indicator (King OF formulation); others use bromthymol blue indicator, which may be more sensitive, but may also be somewhat inhibitory.4 Studies at theCDC revealed that the correlation between Hugh-Leifson and King OF media are excellent and either can be used when interpreting results from Weaver’s tables (CDC approach).3 The sodium chloride and potassium phosphate in the Hugh-Leifson formulation act as buffers and enhance the detection of acid production.

PRINCIPLE:

FORMULAS:

Approximate, per liter of deionized filtered water. (1)Hugh-Leifson OF Basal Medium, Control: Pancreatic Digest of Casein .......................... Sodium Chloride ............................................ Dipotassium Phosphate ................................. Bromthymol Blue ........................................... Agar ............................................................... Final pH 6.8 ± 0.2 at 25°C 2.00 g 5.00 0.30 0.08 3.00

(2)King OF Basal Medium, Control: Pancreatic Digest of Casein .......................... 2.00 g Agar ............................................................... 3.00 Phenol Red .................................................... 0.03 Glycerol ......................................................... 10.00 ml Final pH 7.3 ± 0.2 at 25°C Hugh-Leifson OF Basal Medium With Carbohydrate: Same as (1)above except it contains 10.0 g of a specific carbohydrate.

(3)

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TECHNICAL DATA SHEET #585 REV. 2
(4) King OF Basal Medium With Carbohydrate: Same as (2) above except it contains 10.0 g of a specific carbohydrate.

PRECAUTIONS:*

For in vitro diagnostic use. Observe approved biohazard precautions. Storage: Uponreceipt store at 2-8°C away from direct light. Media should not be used if there are signs of contamination, deterioration (discoloration or evaporation), or if the expiration date has passed. Limitations: Some microorganisms are unable to grow in OF Basal Media and require repeat testing using 2% serum or 0.1% yeast extract.4 Slow-growing microorganisms may not produce color changes for several...