Dichloran-Glycerol Medium

SEIFERTK at NCCCOT.AGR.CA SEIFERTK at NCCCOT.AGR.CA
Tue Nov 28 09:15:52 EST 1995


>From:  OTTGW::IN%"ZUBP40A at prodigy.com" 25-NOV-1995 01:17:23.85
>To:    IN%"mycology at net.bio.net"
>CC:
>Subj:  Dichloran-Glycerol Medium
>
>    I want to know if Dichloran-Glycerol medium (DG18) is used to
>specifically select for xerophyllic fungi or instead protects xerophyllic
>fungi from overgrowth while permitting other fungi to grow along more
>slowly.
>
        Dichloran-glycerol medium. (DG18)
        Both.
        1. DG18 contains a low level of (2 ppm) of dichloran
(2,6-dichloro-4-nitroaniline) which strongly inhibits the growth of Rhizopus
stolonifer and some related fungi, to prevent overgrowth of slowly growing
fungi, especially xerophiles.
        2. It contains chloramphenicol, which combined with low water
activity, positively prevents bacterial growth.
        2. The reduced water activity of DG18 is designed to promote growth
of xerophilic fungi, while slowing growth of spreading nonxerophilic fungi,
especially common soil borne fungi such as Trichoderma, Trichothecium,
Fusarium, etc.  Nearly all Ascomycetes (and Deuteromycetes) will eventually
grow on DG18 if xerophiles are not present.

        In a sense, the question is academic.  DG18 selects for common
xerophiles, including Eurotium species and Aspergillus penicillioides (which
grow very poorly if at all on weak media such as PDA), most Aspergillus
species, and many of the food borne Penicillium species, but will permit
growth of many other fungi.  It is not so inhibitory as to prevent growth of    
Alternaria, Cladosporium or Fusarium, so finds use as a general purpose
isolation medium for a wide range of situations.  It is not designed for the
strict or obligate xerophiles, such as Xeromyces or Chrysosporium - for such
fungi MY50G is essential.

        John I. Pitt
<John.Pitt at dfst.csiro.au>
CSIRO Division of Food Science
P.O. Box 52
North Ryde, N.S.W.  2113 Australia
Phone: +612 887 8525
FAX: +612 887 3107
                   



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