Making Agar Slants - In Pictures

[Wolfy]

Is the condensation inside the tube a problem? Does it end up being taken up by the growth medium or does it just sit there?

I ended up making four batches of agar solution. 1st couple didn't dissolve properly and left the slants really chunky so I washed the tubes all out and started again. By the third time I was satisfied with the consistency of the medium plus I had enough practice to be pretty confortable with the whole process too. Fun little project. Now I'm making a loop out of a thin guitar string and I'll start innoculating this weekend :icon_cheers:

PS: How do you keep your petri dishes sanitary? Is it enough to just tape across them keeping pressure between the halves? I've wraped in glad wrap and taped but it makes it hard to see plus it's not exactly elegant.

Looks good jakub76 - I have no idea how you got the same tubes as I have, I thought mine were some sample batch they just wanted to get rid of.

The condensation is both a problem, and it does seem to get absorbed by the agar over time.
If you inoculate your slants while there is condensation it can cause the newly inoculated yeast to 'run' all over the slant and rather than individual colonies it will just be a carpet of yeast - not really an issue except that it 'looks' different to the 'usual' yeast growth and so it's harder to tell if you have an infection or the like.

I find that 1.5% agar agar works well for me, and it will usually dissolve when the wort gets to boiling point - just need a bit of practice to get it all right.

I use floritsts parafilm (it's much cheaper than the lab stuff) on mine.

But wrapping freshly made plates in cling-film is a common thing to do.

 

[Bribie G]

Bumperty bump

Great guide Wolfy

Due to bad back I can't do any brewing as such but a bit of slanting might be the go, to take the mind off things.

So now I have a couple of packets of Agar threads, some 30ml test tubes , just got a pressure cooker.

I have 4 smack packs of 1469 which are starting to show their age so I'd better get them slanted while the going is good as the 1469 long long drought is upon us once again.
For one smacko would you suggest:

• Smack it and use the resulting liquid to inoculate a heap of slants
• or
• Smack it, do a micro brew with LDME for a few days and use the slurry to inoculate a heap of slants?

The reason I ask is that with an older smacko, even when proved and swollen it can still take an appreciably longer time to build up to pitchable as opposed to an ultra fresh one that can be crawling out of the jar in the same day.
So I'm worried that just using the liquid out of the pack would result in slants that could take forever to culture up.

Or does the actual growing on the agar surface result in a similar yeast count independent of the age of the pack?

I don't have a bunsen burner but I expect a "creme brulee" little blowtorch and some thin gal wire would be good for inoculating?

cheers

 

[Wolfy]

BribieG to inoculate multiple slants you'd not need more than a single drop of the yeasty-liquid from a single smack pack.
Unless the pack was years old and most of the yeast was dead, I can't imagine it would need to be smacked or propagated into a starter.
Since individual cells can be propagated onto malt-agar, there should be many many viable cells on just the one drop of yeasty-liquid (probably too many actually).


I use a similar blowtorch and a loop made from nichrome wire, I guess gal would work fine but, stainless-steel would be better (even a paperclip that bent into an appropriate shape).

Edit: If it was me, I'd wait until you are ready to use one of the packs to make a batch of beer, rather than opening it to take a few drops to make some slants from.