Wort Broth Base

EMD Cat. No. 1.05449.0500
500 g


For the cultivation, isolation and enumeration or enrichment of fungi, especially of yeasts.

According to RAPP (1974), addition of certain indicator dyes to Wort Agar allows differentiation between yeast and bacterial colonies.


Additives


EMD Cat. No. Product Pack Size
LX0021-3 Lactic acid about 90 % purified 500 g



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


Mode of Action
 The accompanying bacterial flora is weakly suppressed by the pH value of 5.0 and largely by a pH of 3.5.

Preparation
Suspend 55 g/liter by heating briefly, dispense into suitable vessels, autoclave (15 min at 121 °C).

Do not overheat. If possible do not reliquefy.
pH: 5.0 ± 0.2 at 25 °C.
 The prepared medium is clear and brownish.
pH: 3.5: Cool to about 50 °C, add approximately 12 ml of filter-sterilized 10 % lactic acid/liter, mix.

  •   Do not reheat.
    Preparation
     Suspend 33 g/liter together with 2.5 ml glycerol/liter, if desired dispense into suitable containers, autoclave (15 min at 121 °C).
     pH: 5.0 ± 0.2 at 25 °C.
     The prepared broth is clear and yellowish-brown.
    Experimental Procedure and Evaluation
     Inoculate Wort Agar by the pour-plate method or by spreading the sample onto the surface of the medium. Further steps depend on the purpose for which the medium is used.
     Incubation: up to 7 days at 28 °C aerobically.

    Quality control of Wort Agar

    Test strains
    		 Growth
    Geotrichum candidum DSM 1240
         		good / very good
    Penicillium spp.
         		fair / good
    Aspergillus niger
         		good / very good
    Trichophyton ajelloi
         		fair / good

    Quality control of Wort Agar (spiral plating method)

    Test strains
    		 Inoculum (cfu/ml)
         		Recovery rate %
    Candida albicans ATCC 10231
         		10³-105
         		70
    Saccharomyces cerevisiae ATCC 9763
         		10³-105
         		70
    Saccharomyces cerevisiae ATCC 9080
         		10³-105
         		70
    Rhodotorula mucilaginosa DSM 70403
         		10³-105
         		70

    Quality control of Wort Broth, Base

    Test strains
    		 Growth
    Candida albicans ATCC 10231
         		good / very good
    Saccharomyces cerevisiae ATCC 9763
         		good / very good
    Saccharomyces cerevisiae ATCC 9080
         		good / very good
    Geotrichum candidum DSM 1240
         		good / very good
    Rhodotorula mucilaginosa DSM 70403
         		good / very good
    Penicillium spp.
         		good / very good
    Aspergillus niger
         		good / very good
    Trichophyton ajelloi
         		good / very good

    Wort Agar:
    Typical Composition (g/liter)
     Malt extract 15.0; universal peptone 0.75; maltose 12.75; dextrin 2.75; glycerol 2.35; potassium dihydrogen phosphate 0.4; ammonium chloride 1.0; agar-agar 20.0.
    Wort Broth Base:
    Typical Composition (g/liter)
     Malt extract 15.0; universal peptone 0.75; maltose 12.75; dextrin 2.75; potassium dihydrogen phosphate 0.75; ammonium chloride 1.0.
     Also to be added:
     glycerol 2.5 ml.
    Literature

    RAPP, M.: Indikatorzusätze zur Keimdifferenzierung auf Würze- und Malzextrakt-Agar. Milchwiss., 29; 341-344 (1974).




    © 2002 Merck KGaA, Darmstadt, Germany