Unusual Media for Bacteria
Mud, Rocks, Sulfur, Light, Hot Springs

This page introduces the interesting world of chemolithotropic bacteria.

Some little known bacteria get energy by oxidizing minerals or from the sun. They eat carbon dioxide and nitrogen gas. There are numerous routes to a life.

To be written

Until this page is written. Try my favorite experiment. put a little soil from any source in a tube, bottle or jar. add a pinch of sulfur, and a few lime pebbles to keep pH acceptable. Set this away in dark or light at room temperature. say 20C. Thiobacillus will grow ; burning sulfur for energy.

Some useful media are shown below.

subscripts and superscripts.

B6 Medium for Thiobacillus

To be completed, I rarely used it.

HAL * Halobacterium Medium



Autoclave Part A and Part B separately. Place 1.5 mL of part B in culture tube. Autoclave and hold near boiling point of water so the agar does not gel. Add 3.5 mL of very hot Part A, cap, mix, and cool as slants. For extreme halophiles. Contaminants probably not able to grow in this high salt. Try this medium when you are trying to isolate bacteria from salt lakes that have salt crystallizing out, such as on the Bonneville Salt Flats or some of the nearly dry lakes in CA and NV.

NFM * Nitrogen Free Medium

    Mo stock solution = 0.1 mg Mo/ml
    Fe stock solution  = 1.0 mg Fe/ml
Combine the ingredients, heat to dissolve, dispense into tubes, autoclave. Sucrose or other sugars may be used, but growth of Azotobacter species varies on other sugars. This medium is mainly use for culturing Azotobacter species as slants. .

RZB * Rhizobium Medium

Make soil extract by autoclaving 400 grams of rich garden soil in 1 or 2 liters of spring water for one hour at 15 pounds pressure. Allow to cool slowly to avoid foaming out of container. Allow to stand a few days (need not be sterile) and decant (pour off) the clear liquid. If you wish you may autoclave again for 15 minues at fifteen pounds and allow to stand for a few weeks to obtain super clear soil extract.
    Use RZB as slants. It gives good growth of Rhizobium species which are found in the nodules on the roots of legumes. Rhizobium species grow well on mannitol which is a rare sugar alcohol.     

SSW * Synthetic Seawater Medium

This medium is excellent for growing most bacteria from the oceans. The glycerol helps bioluminescent bacteria glow as brightly as they are capable. This medium gives bright glow from Vibrio (Photobacterium) phosphoreum provided oxygen is present. Add 10 grams of agar if slants are desired. I maintain all my marine bacteria on slants.

There are simpler ways to make medium. If you live near the ocean and can get full strength seawater (not water from a river), you can use that water and add yeast extract, glycerol and peptone. Or you can get dry seasalt from a pet store and use that for the ocean water. If you don't have peptone, you could use meat flavoring such as bouillon cube or meat broth. You could try some yeast if you do not have yeast extract. I have not tried these substitutes.

WR * Water on Rocks

It is not necessary to autoclave this unless you are making stock cultures. Actually, steaming on 3 successive days may be better as autoclaving 15 minutes @ 15 pounds pressure will melt the sulfur into little balls, but that is not serious as the Thiobacillus can still use it. Adding a chip of limestone or marble to each tube will neutralize the sulfuric acid produced by the bacteria as they oxidize the sulfur. My Thiobacillus survived a year on this medium at room temperature.

--- Some useful info for non-chemists -----

MgSO4.7 H2O is Epson Salt.

NaCl is table salt, but use normal salt not Morton's which contains insoluble aluminum salts which should be harmless but will give cloudy medium. I urge you to use only salt that dissolves to a clear solution. After all, aluminum is the active ingredient in underarm deodorants.

If you don't have all the minerals such as Mg, Ca, Mn, etc. stir soil into spring (or tap) water and let the mud settle a couple days and use the clear supernatant water.

If the chemical you have differs in water of hydrate. Solve a proportion to get the correct amount or just ignore the difference. You can't ignore the difference if you are preparing pH buffers by weight.

You may travel the web to ATCC, NRRL, other media sites. Search for +bacteria +media. For more media formulas. However, the above are more than most students and teachers need.

Revised: 99 Jan 9

Written by Harold Eddleman, Ph. D., President, Indiana Biolab, 14045 Huff St., Palmyra IN 47164

Suggestions, corrections, and comments are appreciated: Contact Harold Eddleman (indbio@disknet.com).