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Biotrue
Stranger


Registered: 07/02/19
Posts: 14
Last seen: 3 years, 2 months
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Pet food agar endospore and contam questions
#26926029 - 09/09/20 10:01 AM (3 years, 4 months ago) |
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I’m trying to make pet food agar work and I seem to get regular contams growing after a few days. Sometimes up to a week later.
I’m wondering if dry cat food contains endospores that are surviving a 45 min instapot cycle on high pressure (probably15 psi). I generally do not get contams on MEA using the same PC cycle and I do my inoculation work under a flow hood. But PFA seems to contaminate almost always.
I’m looking for an alternative to Malt extract agar for when I don’t have it. What’s the best way to avoid contams on pet food agar? Adding antibiotics? Adding peroxide?
I’m also wondering if I soak the pet food for 24-48 hrs if any endospores would reanimate and a PC cycle would be more effective.
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Yeetusdeetus


Registered: 11/23/19
Posts: 1,242
Last seen: 4 days, 1 hour
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Re: Pet food agar endospore and contam questions [Re: Biotrue]
#26926111 - 09/09/20 10:51 AM (3 years, 4 months ago) |
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I’m pretty sure instant pots don’t get as high as 15 psi so you might need to pc for longer. If you’re just getting started with the hobby I’d assume either your flowhood isn’t working correctly or your technique is lacking. It took me a while to develop the dexterity required to not contaminate my plates.
Malt extract is cheap online and a small bag will last for months even if you pour a lot of plates. Totally worth the consistency and ease of prep if you ask me.
Idk about the nutes in cat food agar but it might not be optimal for myc. I’ve only heard of dog food agar and I figure it’s got a lower protein ratio since they’re technically omnivores
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SBurns1369
Lost Wanderer

Registered: 08/29/20
Posts: 17
Last seen: 1 month, 22 days
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Re: Pet food agar endospore and contam questions [Re: Yeetusdeetus]
#26926220 - 09/09/20 12:11 PM (3 years, 4 months ago) |
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Instant Pots on high are 10-11psi for most models.
I generally use my grain water from boiling grains to make agar, instead of LME. I do about 200 ml boiled grain water and 300 ml plain water; with a drop of corn syrup.
Pastywhyte has a widely used agar Tek that uses mashed potatoes flakes.
Pastywhyte Easy Agar
If you don't have potato flakes, you can slice up a potato and boil it for 20 minutes and use about the water from that (I mix to 200ml potato water with 300ml water).
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Mateja


Registered: 07/14/16
Posts: 7,948
Loc: Here
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Re: Pet food agar endospore and contam questions [Re: Biotrue]
#26926777 - 09/09/20 05:16 PM (3 years, 4 months ago) |
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Quote:
Biotrue said: I’m trying to make pet food agar work and I seem to get regular contams growing after a few days. Sometimes up to a week later.
I’m wondering if dry cat food contains endospores that are surviving a 45 min instapot cycle on high pressure (probably15 psi). I generally do not get contams on MEA using the same PC cycle and I do my inoculation work under a flow hood. But PFA seems to contaminate almost always.
I’m looking for an alternative to Malt extract agar for when I don’t have it. What’s the best way to avoid contams on pet food agar? Adding antibiotics? Adding peroxide?
I’m also wondering if I soak the pet food for 24-48 hrs if any endospores would reanimate and a PC cycle would be more effective.
First or all what kind of contamination are you even encountering? Is it mold satellites around the edges from a not so good pouring session? Or is it more like bacterial blotches all over the entire surface of the plates? The latter is basically how your plates would look If you had problems with resilient endospores that germinate after being poured. Identifying the specific non Cubensis cultures growing in your plates will possibly tell you more about what kind of problem you're dealing with. Post pics if you're unsure. 
You probably need to work on pouring plates and sterile Tek in general, and I highly doubt it's contaminating by itself just cause it's dog food. Sterilizing broths and liquids is extremely effective compared to substrates and I've never noticed a difference with pet food agar compared to MEA.
-------------------- Cakes inside Water Tub
Edited by Mateja (09/09/20 05:18 PM)
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