Making Agar Slants (Slopes) - In Pictures

Share your experiences of using brewing yeast.
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greenxpaddy

Re: Making Agar Slants (Slopes) - In Pictures

Post by greenxpaddy » Tue Jul 19, 2011 9:54 pm

I gave it another shot tonight with the same sources of samples. The plates look a lot more orderly and as they have been breathing for a week there isn't the condensation issue any longer. Fortunately the lighting was such that it was very easy to see the sheen of the streaks already made as reference points. I used the gas hob burner on low to create my flame zone.

Do you have any pics of 'clearly failing' plates showing infection you could load up. I think a lot of folk would be glad to see what not to look for!

Wolfy

Re: Making Agar Slants (Slopes) - In Pictures

Post by Wolfy » Tue Jul 19, 2011 10:12 pm

greenxpaddy wrote:Do you have any pics of 'clearly failing' plates showing infection you could load up. I think a lot of folk would be glad to see what not to look for!
I presume they'd look a lot like the picture here: viewtopic.php?f=12&t=35313#p422507

greenxpaddy

Re: Making Agar Slants (Slopes) - In Pictures

Post by greenxpaddy » Tue Jul 19, 2011 10:45 pm

Cheers. Yet again a good read. Is there a normal window of time where it is normally clear if things are not so sterile? You mention months in that post. Are the first colonies of invaders evident after a couple of weeks?

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Re: Making Agar Slants (Slopes) - In Pictures

Post by gregorach » Tue Jul 19, 2011 11:16 pm

Good grief, that's some nasty stuff there Wolfy... And here was me thinking I didn't clean my fridge out often enough!

If you look carefully, most forms of contamination are visible on a plate after just a couple of days. You're basically looking for anything that isn't quite right - unusually shiny colonies, anything hairy or fibrous, or any unusual colours. You need to look very carefully though if you want to catch it early - it can be easy to miss a small colony of something unwanted in amongst all the yeast, and moulds in particular can go from a tiny colony to producing spores (hence contaminating the rest of the plate) astoundingly quickly.

I do have an interestingly weird plate I found in the back of the fridge earlier, but I'd need daylight to photograph it... I'll see what I can do tomorrow.
Cheers

Dunc

Wolfy

Re: Making Agar Slants (Slopes) - In Pictures

Post by Wolfy » Wed Jul 20, 2011 7:35 am

gregorach wrote:Good grief, that's some nasty stuff there Wolfy... And here was me thinking I didn't clean my fridge out often enough!.
:oops: True, but they were specially selected samples to make the photo/example look good. :)

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Re: Making Agar Slants (Slopes) - In Pictures

Post by gregorach » Wed Jul 20, 2011 1:18 pm

gregorach wrote:I do have an interestingly weird plate I found in the back of the fridge earlier, but I'd need daylight to photograph it... I'll see what I can do tomorrow.
No can do, having major IT issues.
Cheers

Dunc

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Re: Making Agar Slants (Slopes) - In Pictures

Post by gregorach » Wed Jul 20, 2011 2:23 pm

Aha! IT issues resolved. AVG Rescue CD - I can't recommend it highly enough.

OK, here's one I found at the back of the fridge yesterday... This was a plate of WLP500 from a sample recovered from one of Calum's brews at the last SCB monthly meeting. Unfortunately, the plate itself was from the dodgy batch - I had thought this one was clean, but it turned out not to be so. Fortunately, I think I got some slants inoculated cleanly before whatever-the-hell-it-is took hold properly... At the time, the streaks of yeast looked perfectly normal, and the interloper was just a tiny star-shaped group of very fine fibres, maybe 1 or 2 mm across, tucked in between two streaks near the edge of the plate, and seemingly embedded in the agar rather than growing on the surface. Very easy to miss. Now, it looks like this:

Image

Cropping in on the affected area (apologies for the poor focus), you can make out a network of fibrous growth, and how the yeast has gone all weird whenever they've come into contact. What you can't see is that it's actually formed a series of pressure ripples in the agar, further confirming my suspicion that it's growing in the medium rather than on the surface, which makes me think it's probably anaerobic:

Image

Oh, and the other thing you can't see it the weird smell it's giving off...

I guess I'll probably want to streak some fresh plates from the slants I took from this and do some further tests before using them. I'm also tempted to order up the necessaries for gram staining and see if I can figure out what this beastie is... Not sure that I want to keep it that long though. ;)
Cheers

Dunc

greenxpaddy

Re: Making Agar Slants (Slopes) - In Pictures

Post by greenxpaddy » Sat Jul 23, 2011 10:16 am

Here's the result of the new plates

First off here is the streak from the rinsed thick slurry off the dubious batch. Wyeast 1098.

Image

Then here is the streak from the beer from that batch that was simply shaken up before a sample was taken.

Image

And last, here is the sreak from the bottom of a bottle of coniston bluebird ale, note a day later. Note there is currently only one colony at around 11 o'clock.

Image

There is some smudging caused by bubbles under the sellotape on the outside of the plates.

'Yeast' hasn't arrived yet....At how many days will a dot be evident from a colony grown from one cell? Some of these earlier colonies my be an amalgamation of a few cells?

Added 18.51 hrs 23rd July

When I looked at these I noticed a shadow on one of the circumferences. Closer inspection later showed a mould growth on that one and the other two had similar infections starting. The container I have been using to store the plates in cannot be as clean as i thought! All the slants are fine and the earliest plates which were cultured soon after pouring but the later ones all have fur developing in the trap area. I should have put each of them in their own sandwich bag! Live and learn! Still, the technique is better.

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Re: Making Agar Slants (Slopes) - In Pictures

Post by gregorach » Tue Jul 26, 2011 12:16 pm

greenxpaddy wrote:'Yeast' hasn't arrived yet....At how many days will a dot be evident from a colony grown from one cell? Some of these earlier colonies my be an amalgamation of a few cells?
Depends on incubation temperature, but I would normally expect something to be visible within 3 days.
Cheers

Dunc

greenxpaddy

Re: Making Agar Slants (Slopes) - In Pictures

Post by greenxpaddy » Wed Jul 27, 2011 7:54 am

Back to slants....

when you have used your slant can we re-use the plastic tube again without risk of infection? i.e. what's the best way to thoroughly clean them out before reusing? Heat them up,pour away, boil a kettle and wash out? Put them in the dishwasher?

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Re: Making Agar Slants (Slopes) - In Pictures

Post by gregorach » Wed Jul 27, 2011 4:13 pm

I find boiling water gets the old agar out just fine. Then I wash them with hot soapy water and rinse thouroughly. If I had a dishwasher that would probably do the job nicely.
Cheers

Dunc

Wolfy

Re: Making Agar Slants (Slopes) - In Pictures

Post by Wolfy » Thu Jul 28, 2011 7:10 am

greenxpaddy wrote:when you have used your slant can we re-use the plastic tube again without risk of infection? i.e. what's the best way to thoroughly clean them out before reusing? Heat them up,pour away, boil a kettle and wash out? Put them in the dishwasher?
I use the handle of a tea-spoon to 'scoop' out the old agar, then soak the vials in my usual brewery-wash (boiling water, Sodium percarbonate and a drop of dish-washing detergent), rinse, allow to air-dry, rinse in acidified bleach solution if I can be bothered and then re-use them.

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Re: Making Agar Slants (Slopes) - In Pictures

Post by Befuddler » Wed Aug 10, 2011 11:02 pm

Cheers for the guide Wolfy.

Just made my first batch of slants using the brewlabs style screw top vials. Lets hope my sterilization was up to scratch.. I couldn't find a pressure cooker on ebay for a decent price so I've gone with the stock pot weighed down with phone books approach.

When it comes to flaming the inoculation loop, do I need to use an alcohol flame to cut down on residue, or is that not an issue? The only decent fire I have in the house is a butane fired soldering iron with a blowtorch adaptor.
"There are no strong beers, only weak men"

Wolfy

Re: Making Agar Slants (Slopes) - In Pictures

Post by Wolfy » Thu Aug 11, 2011 7:08 am

I use the 'brewlabs style' screw top vials for all my yeast slants now, they're much easier to work with.

I use a small butane blowtorch without any problems (that I have noticed), so I presume the butane soldering iron will be a suitable flame-source.
Details/pics of what I use here: viewtopic.php?f=12&t=35313

greenxpaddy

Re: Making Agar Slants (Slopes) - In Pictures

Post by greenxpaddy » Sun Aug 14, 2011 11:48 am

I have finished digesting "Yeast". It gets a bit in depth for most. Luckily being of a science background it was ok. Still I wondered really if you needed that detail. i suppose if you were looking to set up a brewery it would be useful to work out your lab strategy.

There were some important lessons I learnt. The principle one was I realised how much I was underpitching. I wonder if others are doing the same without really realising it.

My normal batch size is pretty much double the standard size and yet I was still using one propagator pack where I was not brewing from slurry. Quite often I was rushing my starters too. True I was actively shaking them but still they were very much underpitched. Not such a problem for wits, where underpitching can really bring out some flavours but not good in ales. This is amplified considerably if the smack pack is old. Even if it was spanking new and 100% viable one x 2L starter is wholly insufficient for a 35L batch.

It is clear now based upon the growth rates Zamel demonstrates that I will need to do a two step starter. A 400ml multiplier from the smack pack. Which then gets split in half between two 2L conicals ( Don't have a 4L conical - and wouldn't be so easy to shake up a bit) I favour using only 1.5L wort in each 2L flask to allow room for agitation.

Overall it was clear that the wort making had become my priority. Whereas it is now clear that making good wort is not too difficult with attention to temperature. The effort should really be focussed to prepare a great yeast culture. How many really focus on that I wonder?

I made an error on these calculations. see my later post on this thread
Last edited by greenxpaddy on Thu Aug 18, 2011 8:42 pm, edited 1 time in total.

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