Colored Yeast?

[KingBrianI]

Alright so I finally got serious about trying to really catch and isolate some yeast from my backyard so I bought some petri dishes and agar and stuff for slants and all that. I put a plate out overnight last week and caught a whole bunch of mold. But there were also a couple of spots of what looked like yeast. Only, in addition to the normal white yeast, there was also what looked like yeast, but one colony was yellowish and one was reddish... Weird. So I took those three colonies and spread them onto a new plate in order to isolate them from all the mold. Here is a picture of that plate:



As you can see, there are three quadrants, each with one of the three yeast colonies from the first plate spread on. Unfortunately I also got a little mold during the transfer. So I'm gonna do another transfer to a new plate in order to get these yeasts isolated further. Only, I wanted to check the collective knowledge here to see if the yellowish and red colonies are actually yeast? I'm not sure how easy it is to tell from the pic, but they really do look like yeast, only colored. Is it possible to determine if they are Brettanomyces or something by color? Anyway, thanks for any help!

 

[aiptasia]

Do you, perhaps, have access to a microscope?

 

[KingBrianI]

Do you, perhaps, have access to a microscope?

Yep, as part of the supplies I bought in order to start yeast ranching I bought a pretty nice compound microscope. I'll definitely be looking at these under the microscope after I transfer some to a new plate.

 

[Yooper]

I have nothing intelligent to say.

But I wanted to tell you that I'm happy to "see" you again! I've missed seeing your around the forum, and I was excited to see a post from you even though I have nothing of any value at all to add to your question, sorry!

 

[passedpawn]

It's a mutation of sacch. Might still brew OK. Search fungal prion.

 

[KingBrianI]

I have nothing intelligent to say.

But I wanted to tell you that I'm happy to "see" you again! I've missed seeing your around the forum, and I was excited to see a post from you even though I have nothing of any value at all to add to your question, sorry!

Thanks Lorena! Between my daughter being born, being diagnosed with cancer, and losing interest in brewing for a while, I haven't been spending much time on the forum for a while. But I've started to catch the bug again, and have brewed 4 batches in the last couple weeks trying to get back into it!

 

[KingBrianI]

It's a mutation of sacch. Might still brew OK. Search fungal prion.

I just did some quick reading on fungal prions - very interesting. At least that seems to confirm that it is S. cervisiea. That would be pretty cool if the red strain had nice fermentation characteristics.

 

[bestbuds]

Microbiologist here.

What media is this? The composition of the media will determine what is able to grow. Any one of those could be bacteria rather than yeast (using a microscope clears up the difference rather fast).

There are also several genera of red-pigmented yeast that are not S. cerevisiae mutants, and may be more likely to show up on a plate from an environmental sample like yours. Rhodotorula can appear bright pink, orange or red. Sporobolomyces will appear salmon-coloured and shiny. Unfortunately, I don't think that either can ferment the sugars in beer.

The best way to figure out what you have is to look at it under a microscope (maybe ask at a local high school or university). S. cerevisiae should be easy to distinguish from these other yeast under the microscope.

Another, minor thing that is easily fixed: Try streaking to dilution (http://amrita.vlab.co.in/?sub=3&brch=73&sim=213&cnt=1) so that you get isolated colonies. Colony morphology gives us a lot of information toward species identification!

 

[KingBrianI]

Thanks for the info bestbuds! The media is 1.040 unhopped wort with 1.5% agar powder. I didn't get around to looking at them under the microscope last night but I'll do it tonight and try to take pictures. I'm also familiar with streaking to dilution, and will do that when I plate up each of these onto separate plates.

 

[passedpawn]

Cool, I love yeast pics.

 

[KingBrianI]

I re-plated each of the samples onto new plates and streaked in such a way to hopefully isolate some cells. I also took a look at each of them in my microscope and took some pictures. Holding an iphone up to the eyepiece and trying to take a pic isn't so easy so the pics are kinda crappy. Hopefully, they show enough to be useful though. To me, it looks like the white and red organisms are both Saccharomyces while I'm not sure about the yellow organism. The cells were much much smaller than the yeast I'm used to seeing. Anyway, here are some pics.

(I apologize again for the crappy quality. In many cases the cells were many layers deep and I could only get a thin plane in focus at once.)

White at 400x


white 1000x


red 400x


red 1000x a (there are a lot of roundish cells in the red sample in addition to the yeast looking things)


red 1000x b


yellow 400x


yellow 1000x