Home | Community | Message Board
You are not signed in.
Sign In New Account
Forum Index Search Posts Trusted Vendors Highlights Galleries FAQ User List Chat Store Random Growery

MushroomMan Mycology
This site includes paid links. Please support our sponsors.

Mushrooms, Mycology and Psychedelics > Mushroom Cultivation
Threaded Mode Threaded  Previous topic Previous  View all topics Index  Next topic Next 

Welcome to the Shroomery Message Board! You are experiencing a small sample of what the site has to offer. Please login or register to post messages and view our exclusive members-only content. You'll gain access to additional forums, file attachments, board customizations, encrypted private messages, and much more!

Shop: Myyco.com Isolated Cubensis Liquid Culture For Sale   Mushroom-Hut Substrate Bags, Substrate Mix   Sporeworks.EU Spores for European Microscopy

Jump to first unread post Pages: 1
Some of these posts are very old and might contain outdated information. You may wish to search for newer posts instead.
Bacterial contams - agar
    #6081306 -

I am getting a lot of bacterial contams in my agar lately and I am trying to find the source.

my PC time was 1 hour at 7.5 psi
glovebox is sanitized by spraying 70% alcohol
agar is poured and inoculated in a still air glovebox

I inoculated 7 plates and left three blank. All inoculated plates grew bacteria. Blank plates also grew bacteria but the colonies developed 10 days later.

I am sure that the inoculum is contaminated because of the difference between inoculated and blank plates. There must also be another source. What should be the first step to change (PC pressure and duration, glovebox sanitation, other)?

Extras: Filter Print Post Top
Re: Bacterial contams - agar [Re: Owl]
    #6081510 -

It might be perfectly normal. We use agar to transfer the healthy mycelium away from the naturally occuring contaminants. As the agar cools after pouring into petri dishes, it shrinks, drawing in contaminants from the air, which is full of bacteria and mold spores.

It's important to wrap your petri dishes with parafilm as soon as they solidify after pouring.

When you see contamination developing in a petri dish, immediately transfer any good mycelium away from the contaminated dish into a fresh one.

It will help to use a filtered flask for PC'ing your agar to avoid contaminants being drawn into the flask as it cools. Allow the agar to cool until it's nearly solidified before pouring. This will cut down on the temperature differential between inside and outside the petri dishes, reducing the amount of contaminants drawn in as the dishes finish cooling.
RR


--------------------
Download Let's Grow Mushrooms



semper in excretia sumus solim profundum variat

"I've never had a failed experiment.  I've only discovered 10,000 methods which do not work."
Thomas Edison

Extras: Filter Print Post Top
Re: Bacterial contams - agar [Re: RogerRabbit]
    #6085543 -

Thank you for the tips. Yesterday I noticed that the potato broth (I use PDYA recipe) was extremely small for one litre. I probably forgot to turn down the heat when boiling the potato's, making the broth too concentrated and ending up with a media that favors bacteria instead of fungi.

Extras: Filter Print Post Top
Re: Bacterial contams - agar [Re: Owl] * 1
    #6086826 -

You still need to wrap the petri dishes with a breathable filter tape of some kind, even if left in a glovebox. Petri dishes don't seal by themselves so will definitely contaminate if not wrapped. I use Parafilm.
RR


--------------------
Download Let's Grow Mushrooms



semper in excretia sumus solim profundum variat

"I've never had a failed experiment.  I've only discovered 10,000 methods which do not work."
Thomas Edison

Extras: Filter Print Post Top
Jump to top Pages: 1

Shop: Myyco.com Isolated Cubensis Liquid Culture For Sale   Mushroom-Hut Substrate Bags, Substrate Mix   Sporeworks.EU Spores for European Microscopy

Mushrooms, Mycology and Psychedelics > Mushroom Cultivation
Threaded Mode Threaded  Previous topic Previous  View all topics Index  Next topic Next 

Similar ThreadsPosterViewsRepliesLast post
* Bacterial Contam in MEA upupup 2,938 7 11/23/02 11:38 AM
by Seuss
* When using agar dishes wouldn't it be wise too TheGreenLantern 1,785 3 04/13/02 01:35 PM
by ParticleMan
* Removing bacterial contam from cake? (kinda urgent) ykk 2,607 2 07/25/02 05:31 AM
by Killa420
* Cool! Successful agar dishes...what now....? Frankenstein 2,627 3 04/11/02 07:55 AM
by Anno
* bacterial contam?? flein 1,746 1 06/16/02 09:23 AM
by Karen
* Bacterial Contam in PF Jars? Looking for pics to compare havatampa 2,296 3 11/03/03 01:12 PM
by havatampa
* old agar dish boomer420 1,403 8 04/14/04 07:08 PM
by thisspock
* made agar dishes, now what? thisone 1,516 3 11/14/03 06:45 PM
by thisone

Extra information
You cannot start new topics / You cannot reply to topics
HTML is disabled / BBCode is enabled
Moderator: Shroomism, george castanza, RogerRabbit, veggie, mushboy, fahtster, the_chosen_one, LogicaL Chaos, 13shrooms, hamloaf, cronicr, Stipe-n Cap, Pastywhyte, bodhisatta, Tormato, Land Trout, A.k.a
3,582 topic views. 12 members, 236 guests and 136 web crawlers are browsing this forum.
[ Show Images Only | Sort by Score | Print Topic ]
Search this thread:

Copyright 1997-2026 Mind Media. Some rights reserved.

Generated in 0.024 seconds spending 0.007 seconds on 14 queries.