Yeast Slants

[Spartan 117]

Hey Guy's

Been reading on the net on how to make yast slants. I understand the whole preperation process but am unsure about what to do then. Do the slants (like bacterium cultures) need be incubated at a certain temperature and when I have collonies of yeast do I just keep them in the fridge? If so for how long should they be incubated and how long will they keep in the fridge?

Cheers

Aaron

 

[Thirsty Boy]

you incubate them at a nice moderate room temperature for a few days - you will see the yeast growing on the surface of the gel. I like to give my slants a week or so at room temp, so that if there is anything apart from yeast growing on there, I will have a better chance of seeing it. This may or may not be good practice from a yeast viability point...

Then store in the fridge at 4C

I was reading in a recent brewing industry mag (Brewer and Distiller I think) that with the exception of -80 cryogenic storage, slanting and storage at 4C (with reculturing every six months) was the best way to maintain yeast cultures in good, stable condition with a minimum of drift in the fermentation properties of the yeast.

TB

 

[~MikE]

oooh yeah -80C freezer.

yeast slants should be fine for a week at room temp. you can tell when cell viability is dropping off as the yeast itself slowly turns brown from it's nice pasty white as cells die off.

 

[Spartan 117]

Cool, exactly what I nedded to know. Seems like a nice way to save money, growing your own yeasties.

Aaron

 

[gwozniak]

Do you guys use that agar stuff as the medium or do you use something else?

 

[Spartan 117]

Do you guys use that agar stuff as the medium or do you use something else?

I'll be usig agar, but only because I'll be getting it free from Uni , I'll also try to get my hands on some test tubes if they'll let me.....

Aaron

 

[buttersd70]

Some use geletin, some (if not most) use agar. One of the main complaints (from others, that I've read in other threads) with geletin is that it doesn't set firm enough. I use agar.

Personally, when I make a bunch of blanks, I keep them for several days at room temp before I innoculate them, just to be absolutely sure that they're OK. My first batch I had 2 duds that started growing stuff....

 

[~MikE]

don't use gelatine, just don't unless you absolutely cannot get agar.

 

[gwozniak]

So where do you get agar from?

 

[altone]

So where do you get agar from?

Your local asian supplies store.

 

[Spartan 117]

So where do you get agar from?

Asian grocers usualy by what the internet says. and if you cant get it there im sure someone here will know of a source.

Aaron

 

[gwozniak]

Hahaha,
And here i was thinking i'm gonna have to make contact with a bio weapons lab

 

[gava]

I use gelatine and all my slants work fine...

don't use gelatine, just don't unless you absolutely cannot get agar.

 

[samhighley]

Gelatine is not as stable as agar at warmer temperatures, which makes it a pain in the arse if you live in warmer climates.

Agar will remain solid until very warm temperatures (60C+) while gelatine starts to turn back to liquid at temperatures around 30C.

Go with agar if you can find it. I get it at the local asian grocers. It's the same as the one listed on the Beerbelly page.

 

[gava]

Ah, that would be a pain in hotter places..I have a temp controlled area for growing the yeast then i keep mine in a fridge. no real risk of turning back into liquid.

Is Agar more expensive than Gelatine?

Gelatine is not as stable as agar at warmer temperatures, which makes it a pain in the arse if you live in warmer climates.

Agar will remain solid until very warm temperatures (60C+) while gelatine starts to turn back to liquid at temperatures around 30C.

Go with agar if you can find it. I get it at the local asian grocers. It's the same as the one listed on the Beerbelly page.

 

[raven19]

FWIW, I use Gelantine, and use it in a 50/50 mix with malt... made up to around 1040. This seems to set quite well at room temps.

My first slants did not have enough gelatine in them, hence melted a bit.

 

[~MikE]

Ah, that would be a pain in hotter places..I have a temp controlled area for growing the yeast then i keep mine in a fridge. no real risk of turning back into liquid.

Is Agar more expensive than Gelatine?

not really, i get 42g pack for $2 - is enough for just over 2L of media.

gelatine melts if the slants get warm. yeast love growing at 30C, gelatine loves melting around that temp . agar sets at room temp, no need to put it in the fridge, you can leave it at room temp for weeks and it'll be fine, unlike gelatine. if your culture (this shouldn't be the case with yeast though) produces proteases then it will dissolve the gelatine and leave you with liquid. there's quite a few reasons not to use gelatine, but if you have to, it will work.

 

[samhighley]

Melting slants is a royal PITA. Go for agar. It's cheap and readily available.

 

[Bribie G]

Not too lazy to do a search, just while this thread is live at the moment where do you guys source your test tubes and what $$$ ? What's the best type of tube, plastic or lab quality glass? Do they have pop on or screw on lids? If pop on then do you seal them by dipping them say in melted candle wax like some winemakers with their corks??

Why so many questions two dogs? :icon_cheers:

 

[pdilley]

Not too lazy to do a search, just while this thread is live at the moment where do you guys source your test tubes and what $$$ ? What's the best type of tube, plastic or lab quality glass? Do they have pop on or screw on lids? If pop on then do you seal them by dipping them say in melted candle wax like some winemakers with their corks??

Why so many questions two dogs? :icon_cheers:

Plastic or Glass. Glass is what I have used in the past and glass is what the yeast meisters at the club use.
I have not bookmarked any web sites but there are a few good laboratory and medical supply mail order firms out there, others will probably chime in.

Wort and Agar are cheap so most people don't get bothered with the waste of surface area by buying large capacity tubes and just filling them up. That said, you only use the increased surface area created by turning the tube on its side to set the agar at an angle and not the 3/4 of a giant tube of wort poured beneath it. You work on the surface with Agar, not through the substrate -- for that we have specialty gels for 3-dimensional work.

Tube holder frames are cheap, plastic jobs you snap together yourself. The only problem is most are not slant holders so you have to prop them at an angle until the agar sets. Another option is to get tubes with sides that extend down to the bottom past the dimple or cone and can set upright on their own. Because surface area is all you want you can also look at anything wide and squat and forget about slanting them - something closer to the petri dish which is what you really want anyway for surface area, which is why they were invented and used, just that most glass petris do not have screw on lids.

Most of this is sold at a price per lot of items. Expect anywhere from $20 and up for a set of tubes with screw on caps. Qty depends on what its made from and what size (you can also use some Cetrifuge Vials as tubes as well as some have good seals. Plastic frames are $10-20 range.

I'm going to see about getting my borosilicate petri plates and sample vials brought over from the states as I have a huge collection just sitting around in storage


EDIT: If you have a pressure cooker already then you are set. You can do sterilisation lab techniques (steam + pressure is the most effective per cost) as well as santisation techniques (just boiled on stovetop at standard atmospheric pressure)

Cheers,
Brewer Pete