I won't rehash my previous questions other than to say I've followed the directions implicitly and produced 12 blank slants which were being stored in a sterilized ziplock bag with lids tight and electrical tape sealing. The unused slants were made about 2 months ago. Upon examining them today I noticed one slant was completely corrupted by green mold. A couple of others had a light film of mold. Any ideas what went wrong? I actually pressure cooked the mixture filled vials a little longer than the directions implied. Where was the mistake? Should I assume the good looking slants are still okay? If they were supposedly sterile they should have lasted indefinitely, even if they hadn't been inoculated yet. I don't see how the slants could have been contaminated during the brief moments of lifting them out of the pressure cooker, tightening the lids, and wrapping them with the tape. Thank you!
How many of you that use slants also use plates?
Technically, if you slant you should be plating first to assure a pure single colony was used. I plated before I slanted.
Yea, thats what I plan on starting with. I just really havn't seen too many posts of people using the plates. So what is your technique. My plan is to get the fresh yeast vial, steak onto a plate and incubate that. Then when needed transfer to a slant and grow up that until ready to create my starter? Does that sound about accurate?
So I am attempting to make plates. Trying to just get down the right process before I actually start plating yeast.
How thick should the plate media be? Haven't really been able to find a proper answer. I poured maybe 20-30ml into the plate. Should I try to make it as thin as possible?
Alright the first test run of making plates was a semi-success. After I poured in the media into the hot plate I covered and let cool and set. After they set I have read that you should turn them upside down to get rid of the condensation that is built up on the covers. I did this and then after a few days I flipped them back over and that is where I think I ran into the problem. Two of the 4 have grown some funkyness, the other two are doing ok for now.
Is that common practice to get rid of the condensation. Or am just not pouring the media hot/fast enough?
Alright the first test run of making plates was a semi-success. After I poured in the media into the hot plate I covered and let cool and set. After they set I have read that you should turn them upside down to get rid of the condensation that is built up on the covers. I did this and then after a few days I flipped them back over and that is where I think I ran into the problem. Two of the 4 have grown some funkyness, the other two are doing ok for now.
Is that common practice to get rid of the condensation. Or am just not pouring the media hot/fast enough?
How many of you that use slants also use plates?
It's not that I do not trust the purity of yeast producers. It's that I know that most liquid cultures are not 100% pure. Without a means by which to verify the purity of a liquid culture, one must assume that it carries a wild microbial load in addition to the domesticated yeast culture. A well-isolated colony on a plate is almost guaranteed to be 100% pure.
Here's what can happen when one inoculates slants directly from liquid cultures:
Have you actually found that vials of commercial yeast contain mold?
So this is exactly what I did with three plates. Proofed them for three days ad they looked great. Streaked them with washed Conan yeast. After two days had nice signs of growth. This was Friday and I had kept the thee plates upside down covered with al foil.
This was last Friday. Returned home from a weekend trip Sunday prepared to slant the findings only to reveal mold growing on all three plates. I had moved them from under the foil to inside an open ziplock bag
I assume this was a result of leaving them upside down. In any event I slanted five small colonies far away from the mold. I plan to do a 1 gallon batch of beer this weekend with one of the slants to proof it out.
The key to them is the yeast cells that you want out-compete anything else in the wort making minor issues inconsequential.
Question for those who slant yeast:
When you are propagating a culture to pitch to a beer, how do you estimate your starting cell count? Ie: when you are calculating your starters and how many cells your beer will need, what number do you start with in the calculator? 1 million? More? Less? RDWHAHB?
Does anyone take a loop from the wyeast smack packs? I will be getting the three private collect yeast starins 1203, 2487, 3864, and would like to streak a plate with each. Does anyone have any tips or should I just take the loop after I pour the yeast out into my starter? What about make a sterile wort in a 50ml beaker and than dumping some of the smack pack into that, like a small starter and than using that to plate from?
I am not sure what I am doing wrong with making the media. I measure the amounts and put in a flask to boil for a minute. Than I pour into a beaker and autoclave the media for 20 minutes. After I pull out the beakers and vials, each one has clumps in the bottom. It never looked like that when I added the media before autoclaving it.
i have moisture in my slants. the medium dried solid but each slant had a little moisture on top after drying and then when I stand the slant up the moisture runs under the slanted medium and the medium spins around in the slant.
will this be a problem? I've tried making slants twice and it happened both times. I boil the dme and agar before adding to th slant for 15 minutes so everything is disolved and mixed together well. it seems the moisture is from the steam from the pressure cooker and it doesn't mix in with the medium wbile drying. I cant find any information about this.
me recipe is:
300mL of water
4 grams of agar
22 grams of DME
2 grams of nutrient
Enter your email address to join: