Methods for detecting a xerophilic or osmophilic yeast or mold microorganism

1. A method of detecting yeast or mold microorganisms in a sample; the method comprising:

mixing a sample with an aqueous diluent to form an inoculum;

wherein the aqueous diluent comprises about 1.0 to about 10.2 weight percent glycerol;

contacting a predefined amount of the inoculum with a growth region of a thin film culture device, the device comprising:

a waterproof substrate having a top surface and a bottom surface;

a dry, cold water-reconstitutable medium fixed to and covering at least a portion of the top surface of the substrate, the medium comprising a gelling agent and, optionally, a mixture of nutrients to support the growth of a microorganism;

wherein the gelling agent comprises guar gum, xanthan gum, locust bean gum, or a mixture of any two or more of the foregoing gums;

after contacting the predefined amount of the inoculum with the growth region, incubating the thin film culture device for a period of time at a temperature suitable for growth of a yeast or mold microorganism; and

detecting a presence or an absence of colony of the yeast or mold microorganism in the growth region.

2. The method of claim 1 , wherein the aqueous diluent comprises about 1.0 to about 5.1 weight percent glycerol.

3. The method of claim 1 , wherein contacting the medium with the predefined amount of the inoculum further comprises contacting a predefined area of the medium with the predefined amount of the inoculum.

4. The method of claim 1 , wherein the device further comprises an air-permeable membrane having an upper surface and a lower surface, wherein the lower surface of the membrane is fixed to and covering at least a portion of the top surface of the substrate, wherein the reconstitutable medium is fixed to and covering at least a portion of the upper surface of the membrane so as to define a growth region.

5. The method of claim 1 , wherein the method further comprises providing a detection reagent, wherein contacting a predefined amount of the inoculum with a growth region of a thin film culture device comprises forming a reconstituted medium comprising the detection reagent.

6. The method of claim 5 , wherein the detection reagent comprises an enzyme substrate for a phosphatase enzyme activity.

7. The method of claim 1 , wherein incubating the inoculated thin film culture device comprises incubating the reconstituted medium at 25 degrees C. for 72 to 168 hours.

8. The method of claim 1 , wherein detecting a presence or an absence of colony of the yeast or mold microorganism comprises detecting the presence or the absence of an osmophilic yeast microorganism or a xerophilic mold microorganism.

9. The method of claim 8 , wherein detecting a presence or an absence of colony of the yeast or mold microorganism comprising detecting the presence or the absence of a yeast colony.

10. The method of claim 9 , wherein the yeast colony comprises yeast cells of the genus Zygosaccharomyces.

11. The method of claim 8 , wherein detecting a presence or an absence of colony of the yeast or mold microorganism comprises detecting the presence or the absence of a mold colony.

12. The method of claim 11 , wherein the mold colony comprises mold cells of the genus Fusarium.

13. The method of claim 1 , wherein the aqueous diluent comprises an effective concentration of peptone for facilitating recovery and/or growth of the yeast or mold microorganism.

14. The method of claim 13 , wherein the aqueous diluent consists essentially of 0.1% (w/v) peptone and about 1.0% (w/v) to about 10.2% (w/v) glycerol.

15. The method of claim 1 , wherein incubating the thin film culture device for a period of time comprises incubating the thin film culture device with a bacteriostatic or bacteriocidal agent included therein.

16. The method of claim 15 , wherein the bacteriostatic or bacteriocidal agent comprises chloramphenicol, chlortetracycline, tartaric acid, or a suitable penicillin.

17. The method of claim 1 :

wherein the thin film culture device further comprises a cover sheet having a first surface and a second surface, wherein the first surface comprises a second dry gelling agent adhered thereto;

wherein the method further comprises placing the device over the cold water-reconstitutable medium;

wherein placing the device over the cold water-reconstitutable medium comprises contacting a portion of the first surface of the device with the reconstitutable medium.

18. The method of claim 17 , wherein the second dry gelling agent comprises guar gum, xanthan gum, or a mixture of guar gum and xanthan gum.

19. The method of claim 9 , wherein detecting a presence or an absence of colony of the yeast or mold microorganism comprises detecting a metabolic product of a detection reagent.

20. The method of claim 1 , wherein incubating the thin film culture device comprises incubating the reconstituted medium at 25 degrees C. or at 28 degrees C. for 72 to 168 hours.