Starter from yeast slant

[exploding_monkeyface]

I'm trying to make a starter from a yeast slant of Bell's house strain. I've followed the instructions in the wiki, located here

The guide says to feed the 250ml starter the next day with 500ml of wort. The question is, should I already be seeing activity from the 250ml starter prior to adding the 500ml or do I just go ahead and add it?
I'm not seeing any activity at all at this point.

 

[bja]

I couldn't read all that but this is how I do it, and you won't see much activity in the beginning.

First, add enough wort to the slant to almost fill it. Mix it up and cover it. Leave it for a day.

Then add the wort in the slant to 50 ml wort. Let that sit for 2 days. Put this on a stir plate if you can. I use a 150 ml beaker.

Add this wort to 1/2 to 1 liter of wort and let ferment for 2 days and you should then have a nice yeast cake to work with.

 

[Warthaug]

I wouldn't follow bja's method, unless you're planning on using your slant only once. Nor would I follow the one in the wiki, as a step-up from a slant to 250ml of wort is one hellof a large jump in volume - which is both inefficient (from a yeast-yield perspective) and a high-risk of infection (low pitch numbers = better opportunity for bacteria to contaminate). Here is how I do it:

1. Prepare a small tube of sterile wort; 5-10ml is suffient.
2. Using a sterile loop or sterile toothpick, grab a bit of yeast off of the slant and innoculate your tube.
3. Grow yeast in tube for 24-48 hours at room temp or slightly warmer. Wort should go milky &/or yeast should settle out, indicating growth
4. Pitch this into 250ml of fresh wort, again, grow (with stirring) 24-48 hours until complete - wort should be very milky.
5. Sediment the yeast from the 250ml starter in the fridge; decant the spent wort and resuspend the yeast in either 750ml (if you have a 1L beaker) or 1.75L (if you have a 2L flask) of fresh wort. Stir & grow for 24-48 hours, until complete.
6. Step 5 (sediment eyast followed by fresh wort) can be repeated a second time to further increase yeast numbers.
7. sediment the yeast in your fridge, decant the spent wort and pitch

At all stages "wort" means 1.040 gravity wort supplemented with 2X the normal amount of yeast nutrient. You can forgo the nutrient, but at the cost of ~25% of your yield.

I have a blog post and video on how to do this. In my case I start with frozen cultures; but aside from the storage medium the process is the same.

Bryan

PS: the yeast numbers in the blog post are off, as they were based on Jamils numbers. Using Kai's numbers you get 4 billion yeast after the 250ml starter stage, and either 140 billion (using a 750ml second stage) or 281 billion (using a 1.75L second stage). You will roughly double those final numbers if you sediment & re-pitch the larger volume a second time.

 

[bja]

[*]Using a sterile loop or sterile toothpick, grab a bit of yeast off of the slant and innoculate your tube.

What you're talking about is usually done with a culture plate, not a slant tube. Slant tubes are meant to be used only once.

 

[Warthaug]

I've worked as a microbiologist/immunologist for over 20 years and this is the first time I've heard of a slant being used for temporary storage. Indeed, until the early 1980's slants were the primary form of long-term culture storage.

Bryan

 

[dinnerstick]

i'm with warthaug. do small steps for the reasons s/he says. better for the yeast and way reduces chance of growing something nasty. grow each step until it's really cloudy, or even flocced out. never feed new wort until the culture is really visibly grown.
when i start from a plate, streak, slant or glycerol stock i start in 2-5 ml for the first culture. i incubate at 30c on a shaking platform and even then this step can take a couple days. subsequent step-ups go faster.

 

[bja]

I've worked as a microbiologist/immunologist for over 20 years and this is the first time I've heard of a slant being used for temporary storage. Indeed, until the early 1980's slants were the primary form of long-term culture storage.

Bryan

https://www.homebrewtalk.com/f163/slanting-yeast-133103/

 

[Warthaug]

Those are not slants, despite what the brewer is calling them. They're too small (they'll dehydrate) and they're not so much slanted (slants are angled between 35 and 45 degrees) as they are crooked. Real slants look like this:

Stored in a fridge, a sealed slant should be stable for 3-6 month, under water for ~1 year and under mineral oil for upwards of 10 years. Using a loop you should be able to make multiple "withdrawals" from a single slant.

Bryan

 

[bja]

Those are not slants, despite what the brewer is calling them. They're too small (they'll dehydrate) and they're not so much slanted (slants are angled between 35 and 45 degrees) as they are crooked. Real slants look like this:

Stored in a fridge, a sealed slant should be stable for 3-6 month, under water for ~1 year and under mineral oil for upwards of 10 years. Using a loop you should be able to make multiple "withdrawals" from a single slant.

Bryan

Looks the same to me.