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Testing for LC contamination on agar vs Grain?


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#21 jkdeth

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Posted 20 May 2022 - 01:21 AM

Personally I think sterile is sterile, but I seldom use my agar immediately. And I like doing as much as I can when I run it, so most of the time, my agar is at least 5 days old, sometimes weeks. Now, I get my share of contamination but I haven't had agar show contamination prior to use, unless I obviously screwed up the process, like forgetting to wrap a plate, or forgetting the tape on a pp5 container.

Oh, those plastic mason lids, I wrap those as well. They cant be 100 percent trusted.
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#22 ShortcutSlim

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Posted 20 May 2022 - 01:45 AM

 

I forgot aout the edit time limit. :blush:   @FunnyFamer  . I hunted down the video that PGT did that discussed the LME and Peptone. I watched PGT's video,but didn't think to pause to see what brand he was using. I looked at Amazon,but there were quite a few different Malt Extracts offered and I didn't know if the differences were important or not..

 

Thanks to @sandman for sharing the LME I was looking for.

 

I redid the agar, and as suggested,the condensation was greatly reduced so:

 

Do I need to set the jars right side up and allow some time for any potential contamination to show before testing my LC?

 

Will that small amount of condensation be a problem of any kind?

 

Thx.

 

The contam rate has dropped so much that I pretty much use it after it's cooled down but that being said it's still not a bad idea to let it sit for about 5 days before working with them. I'm not very particular about the LME I use so anything used for beer making will be fine. Don't go overboard on your LME purchase as it is very hygroscopic, I've had powder turn into little tar balls in a matter of seconds, it's really challenging working with it during times of high humidity. A while back I got some empty freezer pop bags to store shroom powder in and they are a better container than the bag it comes in so I transferred the powder. It's still challenging but easier to store and break up the rocks that form over time. Those bags are designed to exclude air and humidity so I use what I need, roll up the end and use alittle binder clip to close it off.
 

 

I understand the humidity issue. I've lived it myself,but it is something I do consider. We don't get much humidity where we are now,but I always have getting out of here on my mind. I appreciate the mention of watching the humidity with the LME. If I could buy and 8oz bag or smaller,I would. I'll never go through a pound I'm sure. I don't know anyone else in the "hobby" locally,or I'd so the halfsies.lol

 

Personally I think sterile is sterile, but I seldom use my agar immediately. And I like doing as much as I can when I run it, so most of the time, my agar is at least 5 days old, sometimes weeks. Now, I get my share of contamination but I haven't had agar show contamination prior to use, unless I obviously screwed up the process, like forgetting to wrap a plate, or forgetting the tape on a pp5 container.

Oh, those plastic mason lids, I wrap those as well. They cant be 100 percent trusted.

 

Good grief. I never considered wrapping the lids. Now I'll be stressing over that. :eek:   I think I'll wait for a few days to test my LC. I know the world is on the edge of it's seat,but they'll just have to wait for the results. :biggrin:

 

Thanks for the help guys. Much appreciated. I'll only get better...hopefully.
 



#23 PerseidTraveler

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Posted 20 May 2022 - 08:12 AM

I use a premixed MAE...last pour was about 3 months ago, did 30 plates and 2 tam'd about a week later. I have about 10 left which are perfectly sterile. I usually lose plates to contamination at that rate, but I feel the visibility on a petri dish is so much better than in jars. I started agar using no pour in jars, and I had no tam issues, but I just felt like I could SEE the mycelium better on petri. Regardless of which method you go with, you will be pleased with agar.
*edit* just saw you've already chosen your method, maybe I should've read the whole conversation before adding my two cents lol

Edited by PerseidTraveler, 20 May 2022 - 08:21 AM.

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#24 FunnyFarmer

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Posted 20 May 2022 - 06:38 PM

I use a premixed MAE...last pour was about 3 months ago, did 30 plates and 2 tam'd about a week later. I have about 10 left which are perfectly sterile. I usually lose plates to contamination at that rate, but I feel the visibility on a petri dish is so much better than in jars. I started agar using no pour in jars, and I had no tam issues, but I just felt like I could SEE the mycelium better on petri. Regardless of which method you go with, you will be pleased with agar.
*edit* just saw you've already chosen your method, maybe I should've read the whole conversation before adding my two cents lol

I'd have to agree with you about the visibility when using petri dishes but I'm willing to deal with the tradeoff for the increased versatility of the jars. The other problem with the jars is getting an agar sample from the bottom, not fun... If only they could make a petri dish with a twist clear plastic lid that you could sterilize over and over I'd be a happy camper.


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#25 PerseidTraveler

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Posted 21 May 2022 - 06:57 AM

FF, I have seen glass petri dishes with heavy glass lids, but they were ungodly expensive...like $19/each or something like that...I'll see if I can find them again and send you a link. They look badass, but I'm not spending $1,000 on petri dishes I might be able to re use if I don't break them lol




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