Potato Dextrose Agar (PDA) Dehydrated, 100 Grams

Update April 3, 2017: The photo of this product has changed, and I see that it is now packaged in a ziplock instead of in a small plastic tub. My review was based on the earlier version. As far as I know the agar product hasn't changed, just the package. I don't change original reviews, I just add updates like this, and that's why the packaging comment might seem off.End of update_________________This potato dextrose agar has made developing my cultures much easier. I have purchased this one time, and used it to make several batches of medium that sometimes included additional additives and other times did not. Cultures have been transferred and re-transferred every 2 - 3 days. I have used this medium with incubation at 77 (+ / - 2) degrees F, at an ambient room temperature of 69 degrees F, and in the refrigerator (temp fluctuates- it is opened a lot). The medium has performed fine in all of these scenarios.I'm using a microwave sterilization technique described elsewhere online (seek and you will find). That procedure does require additional water to make up for the evaporation. The exact amount is going to vary with the amount of agar being prepared, the size and shape of the container used to heat it, and the power of the microwave as that will impact how long you zap it (the range is generally 6 - 9 minutes, I think caution dictates longer as better than shorter, and testing the limits on that is not worth it to me to possibly save 3 minutes at the risk of losing prepared plates). This product has held up to that preparation process, so I do no need to use an autoclave or a pressure cooker, and I am not having any contamination issues. This saves hours. For a general idea, I have been starting with 350 ml distilled water and reducing it to 250 ml. I prepare batches of about 20 - 25 plates at a time, with approximately 10 ml of product in the plates, since I use them immediately and transfer cultures again anywhere from 2 - 7 days. Plates are kept in closed plastic bags during this time, no plastic wrap, Parafilm or other sealing is used, and they have not dried out in a week with this treatment, though for those incubated at a higher temperature it appeared to be reaching the limit. I would not recommend such a small amount of agar if you will be keeping them longer than that; usual procedures call for 20 - 30 ml.Pros: Economical: costs the same or less than buying Agar, potatoes and dextrose all separately.Convenient: I am so happy that I no longer have to cook potatoes, and I am taking better care of my culturessince there are fewer steps to prepare the petri dishes.Effective: The fungi that I culture are growing just fine on this medium. I do not grow bacterial cultures (not on purpose).I am isolating cultures from outdoor foraging and need to keep removing them from the unwanted microbes that are thereby virtue of the mushroom fruiting body or the mycelium having been outside. So, those do show up, as you wouldexpect when doing this. They do not seem to "love it," as this is not what is usually used to culture them, anyway.The fungi are easily outcompeting them on this medium. I should note that I rarely skip a day when checking mypetri dishes, and at the very first sign of any contamination growth I do another isolation procedure. When I haveskipped a day with this product, it hasn't led to ruin. So, by "outcompeting," I mean that the fungi get a faster start.I do not know what would happen if you neglected your dishes; that probably isn't predictable. I do not use any antibiotics.Packaging: The plastic seals out moisture, is wide rather than tall so it doesn't knock over easily and it is super-convenientfor easy measuring right out of the package, and the screw top makes it easy to open without spilling anything.The white container makes it easy to mark your notes right onto it. (I make fewer petri dishes at a time than thedirections specify, so I worked it out just once and used permanent marker to personalize my container.I also have a practice of labeling products that I will purchase again with the source, so that I can easily order more,hand it off to someone else if that person will be taking care of it, or let someone else know where I obtained it without needingto look up that information. So, my container is already marked with Amazon, as I will purchase this again.Directions: The preparation directions, including proportions, are clearly marked on the container. I appreciate not having tolaminate anything, or keep track of some additional paper, and often when I have purchased agar it has come withoutthe proportions or directions. Yes, you can find info online. No, all directions are no the same, so some judgment thencomes into play. Usually that is fine, though you can find descriptions online of people who have their agar fail to gel (thatis with agar in general, not this product in particular) and are trying to figure out what went wrong. So yes, directions matter!These are specific to use with an autoclave, the sterilization procedure used in laboratories.Quality: it is working great, performing well under the conditions described here, and there are no clumps.Cons: I have found none in this product, itself. All I have are a few suggestions that could be considered. It would be nice if the proportions were broken down additional ways, perhaps to match the usual quantity of petri dishes in a package. For example, sleeves of 20 - 25 petri dishes are common. A small chart with the proportions for common quantities would fit nicely on the package. The starting pH of this product could be on the label. Altering pH requires measurements anyway, yet taking one less measurement is a nice convenience. Finally, it would be great if this product could be added to the subscription program on Amazon for those of us who make steady purchases. It is one less thing to remember to order, as that would already be worked out.If you already work with agar or are purchasing for use in a lab, then you will know this next bit so go ahead and skip it. If you are new to working with agar, and intend to use this at home, then it is important to know a few things. Using agar is similar to making gelatin; it has a tendency to clump, so dissolving it properly is essential. I like to start with hot water (some people use cold; doing that has proven more difficult in my experience). Using a pre-warmed, 2 cup Pyrex measuring cup allows me to see the mixture well and to complete the whole process in the same container: dissolving, heating, and cooling. Adding the agar slowly (if you cook, think of the way you just sprinkle something lightly to add it to whipped egg whites) while you are stirring continuously is important. Keep checking with a spoon for any grains that are not dissolved. If you use a cold, metal spoon and it has not dissolved, it may all clump onto your cold spoon. This process takes longer with agar than it does with powdered gelatin, and it has a stronger tendency to clump, so be aware and prepared for that. Agar should be cooled before you pour it into the petri dishes or vials. If you do not have a proper thermometer for this, then you will require one. I find it easiest to monitor the temperature with a thin-stemmed thermometer, as it can remain in the container while everything is well covered to prevent contamination. The temp for pouring cooled agar is 55 degrees Celcius. A water bath is recommended for even cooling. Watch that temperature closely so that your agar does not gel up in the container; it is not time to get involved in something else. With a little practice, you'll figure out the timing that works for you. Nobody can tell you that with enough precision ahead of time, as too many variables will affect the rate of cooling.I have received no discount on this product, made no promises, and have no relationship, interest or profit in the sale of this item. I'm a happy customer, and that's all! I hope that this review, based on my own experience with this product, is helpful to you. Enjoy shopping!

I was new to mycology about a year ago and bought this agar to get into the hobby. I have been extremely frustrated doing agar work and just assumed it was my inexperience. I'm glad to see others are struggling as well. I've had many different cultures barely able to survive, yellow oyster has done the "best", which still took weeks to grow out. Some have shown near zero growth after weeks from both tissue cultures and spores.I'm going to do as others recommend and supplement with actual nutrients and report back. I suspect I'll find the same thing, this really has no nutrients in it... Make your own from some agar agar which is apparently all this is.12/31/21 updateI transferred wedges of about 10 different species from the old agar plates that were made with pure Seaweed Solutions "PDA" to new agar plates that I supplemented with potato flakes, honey and yeast. Every single strain took off 10 times faster than they did on the old plates. I think this is pretty strong evidence that this "PDA" is really just plain agar. I'm so glad to finally know after a year of struggling with agar cultures that it isn't something I was doing wrong.

Works great

Very easy to make...I only prepared a fraction of the package since I only wanted to fill 10 plates. It was fairly simple to make, sterilize and pour after cooling. The only problem is that the culture grew very slowly which could indicate a lack of nutrients. I will see if the second batch grows slowly as well.

good stuff

Product claims to be perfect for mycology and to be potato dextrose agar which it miggv ht be but the amount of potato dextrose is not specified and based on the performance i believe there is very little if any potato dextrose in this mix as the mycelium i was attempting to grow of various species (P. ostreatus, L. edodes, H. erinaceum and others) barely grew at all with terribly sparce growth if there was any at all. This was a waste of my money. DO NOT BUY THIS PRODUCT. I would like to be reimbursed for this purchase but i doubt amazon will refund me. This product sucks for growing mushrooms. It wouldnt even support bacterial life i purposely introduce different kinds of contamination as a control to some of the petri dishes i made with this product and nothing grew. There is clearly NO NUTRITIONAL VALUE IN THIS AGAR DO NOT BUY THIS PRODUCT EVER!!!!!

This is nice clear set Agar... We shall see how it supports the mycelium I dropped in there.I will probably buy this again.

Great product. I put mine in a seperate container and use a little at a time. Works perfect every time!