Bringing Yeast On Slants Back To Life

[mfdes]

I go straight from slant to slant. They still grow fine.
One thing I find is that no matter how well you wrap the lid in parafilm and put the slants inside an insulated mini-eski, the temperature fluctuations still make the slants dehydrate faster than they shold. 1 Year and it's high time I'd refreshed it. I try to do them every 6 months.

MFS.

 

[~MikE]

When moving from slant to slant

I take it the procedure is to add 5-10ml of wort to the original slant - wait for it to fire and then with an inoculation loop

Streak fresh slants

Is this correct?

Cheers

don't even need to do that. loop some cells and streak onto new slant.

 

[Zwickel]

don't even need to do that. loop some cells and streak onto new slant.

hmmm....it sounds like to transfer old cells to just a new agar without renewing the cells itself.

My intension is, to bring the cells to the next generation and store the new generation.
I might be wrong, but I cant see any advantage to store old cells again at a new agar medium.

Cheers :icon_cheers:

 

[TidalPete]

My intension is, to bring the cells to the next generation and store the new generation.
I might be wrong, but I cant see any advantage to store old cells again at a new agar medium.
Cheers :icon_cheers:

+1

TP :beer:

 

[Steve Lacey]

hmmm....it sounds like to transfer old cells to just a new agar without renewing the cells itself.

My intension is, to bring the cells to the next generation and store the new generation.
I might be wrong, but I cant see any advantage to store old cells again at a new agar medium.

No, I think you still renew the generation because you only snaffle the tiniest amount of old yeasties onto the loop and then smear it ever so lightly over the surface of the new agar. The cells will then propagate on the new medium such that you generate 99% new cells from 1% old cells (actual numbers may vary

But having said that, I agree that you will get even better renewal by putting in some wort, letting some fermentation get under way and then looping from that.

Another way is to lift off some of the old yeast into a little sterile water and shake to disperse, then streak from that onto your new agar. It is just a question of starting from a very small number of old yeast.

 

[Sammus]

Ive 'heard' that if the starter wort amount isnt sufficient in size(10ml into a 100ml starter) you are only 'refreshing' the yeast.

To get growth you need more volume.

Have a go at putting 10ml into 250-500 ml of wort....

I read a study on yeast propagation when I was getting into it and for optimum growth you increase starter size in steps of 5x-10x. So 10ml into 100ml is a big as you would want to go. If theres too much food the yeast get lazy and dont reproduce.

 

[mfdes]

You should be actually GROWING the yeast on the slant where they have optimal nutrients and oxygen, for optimal results. You just scrape a bit and smear on the new slant. This will then divide a few times (I leave them 48h at 20 degrees C) to provide you with a new generation of yeast at the optimal metabolic stage for storage, as their glycogen reserves will be at their highest.

Growing the yeast in a liquid medium between slants is far more damaging than beneficial, as the risk for contamination, particularly bacterial, is increased substantially. If I was culturing yeast from a liquid I would plate it first and isolate a pure colony from a single cell before slanting it up. At least that's the standard protocol in our lab.

MFS.

 

[~MikE]

SNIP
MFS.

+1 here. i do micro-work all the time. you're more likely to revive old cells on solid media.