PD agar- commercial vs kitchen?

[Darklight]

Goddamn lumpy, crumpy, hidjus potato dextrose agar, well the homemade stuff anyhow, or am I doing it wrong?

How do youse all do it? I've got almost all the facilities here I need and the stuff was enough to send me screaming for the hills. No idea at all how you kitchen mycologists get by so well with far more basic equipment.

The usual formula- 500g peeled spuds in 500ml H2O boiled etc etc, seived and added 10g/L dextrose, 1g NaOH, balanced pH to 6.5 with 25%w/v lactic acid added gelling agent and autoclaved.

The first thing that happened was that it overflowed during sterilisation and I lost a third ( hint: use a vessel 3x greater than overall volume ).

Then it wouldn't be drawn up into my nifty new raygun looking pipettor, so I had to pour it, which risks extra contamination as the vessel passes over the open plates even if you're careful.

Then I couldn't get it to pour, it was going literally everywhere. I avoid any drips or spills on the outside of plates, discarding those plates b/c no mater how well you wipe them there's still enough of a ladder there for contam to get in. I lost 32% of the plates I poured. Usually I lose 2%

While I was pouring it it was gelling randomly and making big waxy drips from the pour spout, which was making things more difficult as they weree themselves sending off more showers of goop. After a few years experience I am really cautious about putting anything down on any lab surface from which contamination could arise, but I'm going to have to wipe the whole lot down with bleach ASAP as it went practically everywhere except the plates.

Do youse lot put up with this ALL the time? Or did I get the recipe screwed somehow? Has anyone here had experience with the viciously expensive commercial PD agar ( $135 for 500g )- is it any more fluid and easy to dispense? Or should I give up now and just use Malt Extract or something.

[Guest reville]

geez. sounds like fun

um. as far as boiling over what RU using a P/C?

if so just avoid moving it around and dont fill the vessel more than 2/3

add peroxide to avoid contam problems from exposure.

as for the poring it sounds like you used too much agar or you let it cool too far.

BTW i dont use PDA anymore i find everything grows better on milo anyway

[Torsten]

I don't think you stained it well enough. can't remeber, but isn't the solution supposed to be clear?? ie no starch.

[Guest auto302823]

I found soy-amaranth-agar was easier to work with, but I haven't done all that much culturing TBH.

I also found that PDA cooled irregularly, had lots of bubbles, and was generally messier.

[coin]

this is funny heehee ahem..ok, sorry

maybe it is too much starch? i'm a total amature ..i don't know how much difference it would make, but i use only 200-300g potatoes p/l, 10g dextrose, 2g yeast and sometimes a pinch of the end substrate

the other difference is that i use salsa jars, load them with the media, and then cook em.

hehe just thinking of all the goop and the fancy la-di-da hoity toity pipettor

[waterdragon]

i put up a shroom link a while back, i'm sure it had a range of agar recipes on it. try them all and see what suits.

[Darklight]

Originally posted by coin:

this is funny heehee ahem..ok, sorry

Don't be, it was imagine an hysterical darklight alone in her flow hood at 3am pouring Frankenstein goop which threatens to wipe out her pristine culture room environment.

Even I have maternal instincts, misapplied though they be

hehe just thinking of all the goop and the fancy la-di-da hoity toity pipettor

Yep, you got it! Much worse than the struggle in the old days under the perspex tunnel in the bathroom. Very silly...