ATTENUATED-BACKGROUND MICROBIOLOGICAL NUTRIENT MEDIA AND METHODS OF USING THE SAME

1 . A liquid or solid or semi-solid nutrient medium comprising at least one dye or pigment, wherein the nutrient medium supports the growth of a microorganism, wherein the at least one dye or pigment substantially reduces background of the medium, and wherein the solid or semi-solid nutrient medium further comprises a gelling agent.

2 . The nutrient medium of claim 1 , wherein the nutrient medium is disposed in a container and the nutrient medium is proud relative to the container.

3 . (canceled)

4 . The nutrient medium of claim 2 , wherein the nutrient medium is rounded or comprises a flat portion and a circumferential portion that is sloped.

5 - 6 . (canceled)

7 . The nutrient medium of claim 1 , wherein the at least one dye or pigment renders the medium black.

8 . The nutrient medium of claim 1 , wherein the at least one dye or pigment substantially reduces red background, orange background, yellow background, green background, blue background, violet background from exposure to white light, or background from exposure to blue light.

9 . (canceled)

10 . The nutrient medium of claim 1 , wherein the at least one dye and/or pigment provides a peak optical density of between 0.004 and 6.

11 . The nutrient medium of claim 1 , wherein the medium comprises the pigment or the dye.

12 . The nutrient medium of claim 11 , wherein the pigment comprises carbon particles or iron oxide particles.

13 . The nutrient medium of claim 12 , wherein the carbon particles have an average diameter of less than 500 nm.

14 . (canceled)

15 . The nutrient medium of claim 12 , wherein the carbon particles comprise carbon black.

16 . (canceled)

17 . The nutrient medium of claim 11 , wherein the dye comprises an azo dye, wherein the azo dye is acid black 71, acid black 194, acid black 2, reactive black 5, direct black 36, or Nyanza black.

18 . (canceled)

19 . The nutrient medium of claim 1 , further comprising a polymer that binds to the at least one dye and/or pigment, wherein the polymer comprises polydiallyldimethylammonium chloride (polyDADMAC), starch, cellulose, chitosan, β-cyclodextrin, calix[4]arene-based polymers, or a p-tert-butylcalix[4]arene-based polymer.

20 . (canceled)

21 . The nutrient medium of claim 1 , further comprising a free radical scavenger, wherein the free radical scavenger is selected from the group consisting of N-acetyl-L-cysteine, sodium ascorbate, thiourea, nicotinamide, pyridoxine, sodium pyruvate, D-mannitol, 2-oxo-4-thiomethylbutyric acid (OBTA), 3-(methylthio) propionaldehyde (methional), dimethyl sulfoxide (DMSO), tert-butyl alcohol, benzoate, catalase, NADH peroxidase, thiol peroxidase, bacterioferritin comigratory protein, alkyl hydroperoxide reductase, glutathione peroxidase, cytochrome c peroxidase, and rubrerythrin.

22 . (canceled)

23 . The nutrient medium of claim 1 , wherein the microorganism is a bacterium, fungus, protist, or archaea.

24 . The nutrient medium of claim 23 , wherein the microorganism belongs to a genus selected from the group consisting of Acinetobacter, Aspergillus, Bacillus, Burkholderia, Campylobacter, Candida, Clostridium, Corynebacterium, Delftia, Dermacoccus, Escherichia, Exserohilum, Helicobacter, Kocuria, Legionella, Listeria, Methylobacterium, Micrococcus, Mycobacterium, Paenibacillus, Penicillium, Propionibacterium, Pseudomonas, Ralstonia, Salmonella, Selenomonas, Serratia, Shigella, Staphylococcus, Stenotrophomonas, Streptococcus, Streptomyces, Vibrio , and Yersinia.

25 . The nutrient medium of claim 1 , wherein the gelling agent is selected from the group consisting of agar, gellan, sodium alginate, xanthan gum, guar gum, gelatin, agarose, polyacrylamide, and a polysaccharide produced by Rhizobium sp. (CNCM number: I-1809).

26 . The nutrient medium of claim 1 , further comprising nutrients selected from the group consisting of trypticase soy medium (TSM), fluid thioglycollate medium (FTM), Schaedler medium, lysogeny/Lennox (LB) broth, mannitol yeast extract peptone broth, terrific broth II, Super Optimal broth with catabolite repression (SOC) medium, Thornton's medium, Lowenstein-Jensen medium, Sabouraud dextrose medium, D/E neutralizing medium, Loeffler medium, nalidixic acid and colimycin (ANC) medium, and artificial sea water medium.

27 . The nutrient medium of claim 1 , further comprising nutrients from bismuth sulfite agar, Chapman agar, Mueller-Hinton agar (MHA), blood agar, MacConkey agar, trypticase soy agar (TSA), Sabouraud dextrose agar (SDA), Reasoner's 2A agar (R2A), Mueller-Miller tellurite agar, or Tinsdale tellurite agar.

28 . The nutrient medium of claim 1 , wherein the nutrient is solid or semi-solid.

29 . The nutrient medium of claim 1 , wherein the nutrient medium is liquid and disposed within a porous matrix.

30 . (canceled)

31 . The nutrient medium of claim 1 , wherein the nutrient medium has a pH value between about pH 3.0 and about pH 12.0.

32 . A method of detecting the growth of a microorganism comprising:

(a) contacting a surface of the nutrient medium of claim 28 with a sample; and

(b) optically detecting the surface to determine any growth of the microorganism.

33 . (canceled)

34 . The method of claim 32 , wherein optically detecting comprises detecting fluorescence.

35 . The method of claim 32 , wherein step (a) comprises placing a membrane containing the sample in contact with the surface.

36 . The method of claim 32 , wherein step (a) comprises contacting an external surface with the surface.

37 . The method of claim 32 , wherein step (a) comprises allowing air to contact the surface.