Hi Isabel,

I am not aware of any inorganic gelling media for plates. Growing in liquid would be an easier route if you are worried about the potential for your bacteria to degrade and utilze agar (or alternate biologically derived gelling materials) you could try plating on the gel material without any other carbon source and see if they grow. Alternately you could look at the ability of the bacteria to utilize substrates on filter material (nitrocellulose, polypropylene etc.) and saturate these the nutrients you wish to test. (sort of like a southern blot approach to deliver nutrients from stack of paper towels below). Good luck with the project.

Sometimes silica gel is used for thermophiles:

Thermophilic Streptomycete Medium

Composition per liter:

Soybean oil meal......................................................................... 20.0g

Glucose ....................................................................................... 10.0g

NaCl ............................................................................................ 10.0g

Pancreatic digest of casein.......................................................... 10.0g

Silica solution (Ludox) ..........................................................500.0mL

Preparation of Medium: Add components, except silica solution,

to distilled/deionized water and bring volume to 500.0mL. Mix thoroughly.

Gently heat until dissolved. Autoclave this solution and the

500.0mL of silica solution separately for 15 min at 15 psi pressure–

121°C. Cool to 25°C. Adjust the pH of both solutions to 7.0. Aseptically

combine the two sterile solutions. Mix thoroughly. Pour into sterile

Petri dishes in 40.0mL volumes

You can also try "Bactoagar" from Difco. This agar is very often used for isolation of pure cultures of various anaerobes: SRB, methanogens, denitrifiers and others.

However it is not very convenient to use if you aim to cultivate or isolate anaerobes that produce too many acids... like or ex Clostridium like fermenting bacteria... when they grow on huge amounts of sugars in the medium.

Good luck!

Hi Isabel,

we used polydimethylsiloxane (PDMS) as an inert and non-toxic surface for cell cultures. It is easy to handle and can be poured and hardened into any thickness and form. It seems as if there are certain fungi that can degrade that, but in general the capability of metabolizing PDMS is very rare.

Another suggestion would be GelRite, it consists of gellan gum, which only few bacteria can digest and metabolize.

Emil

Hi,

In a special case (looking for polyacrylamide degraders, which I believe are rare?), some colleagues used polyacrylamide to solidify plates. The only trick there was the plates were best poured in an anaerobic hood, since oxygen inhibits polymerization. Once polymerized, oxygen is not a problem. Check the manufacturer's specs, but if sold for electrophoresis PA should be pretty free of other organic compounds. Usual acrylamide cautions apply.

Barbara

Try Silica Gel

Simplified Method for the Preparation of Silica Gel Media

ROBERT C. THATCHER AND TERRY L. WEAVER, 1974

or

Silica Gel as a Microbiological Medium: Potentialities

and a New Method of Preparation

JOHN M. KINGSBURY AND ELSO S. BARGHOORN' 1953

Hi Isabel,

we tried Silica Gels in our lab, but had a rather hard time generating them, and especially adjusting the pH...

I do not work with anaerobes, but with aerobic ultra oligotrophic bacteria which do not grow on conventional plates due to inhibition by to much organic carbon. We had success using gellan gum (e.g. https://www.carlroth.com/downloads/ba/en/0/BA_0039_EN.pdf) as solidifying agent.

Good luck!

Good quality agar is always the best support. It can be obtained from DIFCO or OXOID.