Any microbiologists in the house?

I’m looking for a non-toxic (to ants) fungus-inhibitor and bacteria-inhibitor that I can add to agar nutrient gel to preserve it for an indefinite period of time at 20C.

Anyone? Bueller?

I want to make my own space-age ant farm:

Can’t you just buy some of those and scoop out the gel?

Sodium Azide might be worth a try if you want to roll your own nutrient gel. As far as I can tell it’s not an insecticide, but I didn’t look all that closely.

Although I heard that the FBI might monitor purchases for explosives reasons.

Thanks, Mike. My fact checking on sodium azide reveals that it would be toxic even in small amounts. But, I did some more digging based on that suggestion of yours, and came up with sodium benzoate, the preservative that the Coca-Cola company uses in their soft drinks. It’s only effective in acidic environments, so I would have to lower the pH of the agar solution below 3.6pH.

The reason why I can’t just buy a bunch of these sets and re-use the gel is:

Gels have a property called thermal hystereses: once a gel sets, it requires a higher melting point to reliquify. Agar, for instance, will gel at 30C, but once it’s set, it’ll stay solid up to 90C. I don’t have an autoclave, so it would be very difficult for me to reliquify gel that has already been set.

Not to mention, expensive. They’re selling these for $20 a pop. Food-grade agar is really cheap.

edit… Hmmm. It being Valentine’s day and all, I just came up with a really perverse use for fungus and bacteria-resistant agar… You can make life-size dildos out of the stuff and give them to your sweetheart. So when you say “eat me”, your partner really can! Plus, unlike animal gelatin, agar doesn’t melt at body temperature. The possibilities are endless!

And Jason says no worthwhile research has come from manned space flights. Ha! From 0-G ants tunnelling to edible dildos. Take that!

Wait wait… would that make this a space dildo? Ooooh…

Hmm, I didn’t realize it was that toxic. The stuff I work with that has azide in it doesn’t have warning labels or anything. Not that a sane person drinks lab reagents, but even so. Probably it’s effective as an antibacterial at much lower concentrations than as a poison. Not for home use, though. OTOH I don’t recommend running an ant farm at pH 4, they may not like it very much. Good luck, and maybe I’ll turn up something else for you at work tomorrow.

oh, awesome. i thought one of those ant farms would be a cool present for my nephew, until i saw the price tag ($30 at the store i was at…). buying a $7 ant farm and making your own gel is great idea.

Found this:

Also, are you sure you need this to be antibacterial? You may be able to get away with just sterilizing your container.

I am owned. :(

Ever read one of those threads you suspect will someday be used as “Your honor, the prosecution would like to introduce the evidence…”

The plan is to mix in sucrose, honey, vitamins, and egg white so that the ants can get their carbs and protein from eating the gel. My concern is that without some preservatives, bacteria and fungus colonies would spring up all along the exposed surfaces.

What I’m going to do is set up a traditional ant farm, and experiment with different gel formulas as food. I’ll add preservatives to the formula and see if I can get them to still eat it. If they don’t mind eating it, they probably won’t mind digging in it.

I have a feeling that the sodium benzoate+citric acid is still going to work, because apple juice has a ph of 3-3.5, Coca-cola has a ph of 2.5, and ants dont mind swarming over either substance as long as the sugar is good.

I hope this works. I’d hate to have to invent the space dildo.

That’s some major high-tech food for your ants! :D
A 1% mixture of methyl parabene and propyl parabene (I think equal parts of each) is often used in pahrmaceuticals and skin creams, ointments etc. May also be called metagin and propagin or E218 and E216.

Also, alcohol is a really good preservative. Might be fun in the farm :wink: Naah, they’d propably die…

I didn’t find this after a cursory search, but one thing you should definitely do is find the paper NASA published on this experiment. Not onlly will you learn what to expect, their materials and methods section will describe exactly what they used.