New microscope & yeast -- help verify what I'm seeing.

[olie]

Just got a new microscope, pretty happy with it. ~$265 on Amazon, if anyone's interested.

I've looked at a few tutorials, and a couple of threads here on HBT, so I think I have the gist of it. I haven't set up to count, yet -- these are just 1st-time pix so that I can verify that I'm able to see and identify what I'm looking at.

So that's what this post is about: am I correctly identifying what I'm seeing, here?

For example, here, I think I've got a lot of good yeast cells, and some kind of bacteria. (#2 is closeup of the suspected bacteria).

Below, a few more pictures of things I suspect are bacteria among the otherwise nice field of good, viable cells (and a fair bit of trub for on a couple of them). In particular, I'm interested in the 3rd one down -- where the "bacteria" looks a bit like a teeny-tiny whale. Is that perhaps trub?

The slide is dyed, and what I think I have here is lots & lots of viable cells with a handful of stray dead ones, right?

Lastly, I think I've interrupted my yeast mid mitosis; is that what I'm seeing, here?

Thanks a ton for your help! Looking forward to getting good at this and begin making starters and start re-using yeast -- woot-woot!

 

[bovine_OB]

Looks like debris. Bacteria will be much smaller. In the second pic, the close up one, toward the right edge of the debris there is a dark for. That is the size of a cocci shaped bacterium.

 

[olie]

Bacteria will be much smaller.

So like in the 6th one (the one after the "whale")? A straight "rice" shaped thing about the size of a yeast cell...?

 

[Vale71]

Bacteria have more "rounded" shapes without sharp edges. Yours look more like shards so it's probably just suspended inert solids.

 

[CodeSection]

Just got a new microscope, pretty happy with it. ~$265 on Amazon, if anyone's interested....

That sure beats the two I have....pretty fancy with being able to view it on the computer and to make pictures of your sample! Your post sorta makes me want to find where I put mine in storage. Neither has the capability of what yours can achieve.

 

[ESBrewer]

Those large things with edges could be some crystals and there is probably some debris, too. The smaller rod shaped thing could be large rod-shaped bacteria. It is true that most bacteria are smaller than the brewing yeast and some may be difficult to see, depending on their size, optics & staining used. See this. There are also larger living things that can end up in samples like human cells from skin, protozoa etc.

 

[bierhaus15]

Looks like lot of organic material - trub, protein, ect, - and some silica inorganics. That yeast does not look very healthy though, lots of petite and irregular shaped cells. If yeast counting or looking for contaminates, you'll really want a cleaner sample. Was this old or stored dried yeast?

 

[isomerization]

Didn’t see anyone respond regarding your staining image, but yes, dead cells will be unable to actively pump out your dye (typically methylene or trypan blue) wheareas live/healthy cells will be able to. If you’re counting, you’ll want a hemocytometer for accurate, reproducible results.

 

[olie]

That yeast does not look very healthy though, lots of petite and irregular shaped cells. If yeast counting or looking for contaminates, you'll really want a cleaner sample. Was this old or stored dried yeast?

Yes, this is old yeast (though I have older ) from last August, I think.

Actually, I guess I should ask: is that old? It's been in the refrigerator the whole time, but otherwise uncared for. As I don't yet wash & harvest yeast -- I've just collected a few jars so that I can practice staining & counting & IDing what I see -- I haven't taken any special measures to treat it very carefully, other than keep it clean.

I am a bit surprised to be told that I'm not seeing a single bit of bacteria, though! Sure, I work very hard to be crazy-sanitary with everything, but I'd've expect some bacteria to get through my defenses, no? I had to search around the slide for a LONG time to find even these guys, which I'm now learning is just more junk.

Oh well -- "good problem to have", I suppose! Now I need to go learn more about how to tell weak/unhealthy yeast from strong & healthy.

WRT cleaner sample: yeah, this hasn't been washed or anything; "first separation". Again: it's "learning yeast"

Hmm, that was a bit rambling. The follow on questions from this reply:

1) Is it unusual to not be able to find any intruders in a yeast sample?
2) How long is "a long time" for carefully stored yeast (sealed, sanitized mason jar in refrigerator)?
3) How to identify weak vs strong yeast?

Thanks!

 

[bierhaus15]

For most thick yeast slurry, you'll want to do a 1:100 or 1:1000 dilution with sterile-distilled water (generally...it depends). You want around 100 yeast cells in the microscope field of view (at 400X). The yeast dilution is then analyzed and at that level any indication of pedio is considered contaminated. For lacto, 5-10 rods per ml is often below the spoilage threshold for beer stored below 40F. I think the Yeast Book contains info for yeast counting, process, ect. Otherwise, the ASBC methods are the gold standard.

And while this is not a popular opinion, bottom cropped yeast slurry stored for more than 2 weeks is not ideal. In commercial breweries, you might go that long with optimal harvest and storage methods, but for home brewing those conditions are not being met. Yes, that yeast will still make beer, but it will not produce a beer as good as one using fresh and healthy yeast.

 

[passedpawn]

I agree with most comments above (didn't read all). Some of the pictures contain what looks like debris. Bacteria are pretty easy to identify - little broomsticks there.

The following is a timelapse video I made of some bacteria (lactobacillus delbruckii). 30 minutes of growth IIRC. I grew this on an agar plate, I think while preparing to inoculate a berliner wiesse. The depth of field is very very shallow, and it loses focus presumably due to the colony thickening while growing.

 

[passedpawn]

And yes, that's cell mitosis. Good picture!

 

[Vale71]

And yes, that's cell mitosis. Good picture!

Tsk, tsk. Yeast reproduce through budding, not mitosis...

 

[passedpawn]

Tsk, tsk. Yeast reproduce through budding, not mitosis...

It's mitosis - by budding.

 

[day_trippr]

^troo fact^

 

[isomerization]

It's mitosis - by budding.

I assumed it was sarcastic ribbing, but maybe not?

 

[RPh_Guy]

Sometimes it's difficult to detect sarcasm with the Italian accent.

 

[olie]

I assumed it was sarcastic ribbing

That's what I read.

I also read a heavy "waht*EV*ar...!"

 

[passedpawn]

I assumed it was sarcastic ribbing, but maybe not?

Sometimes it's difficult to detect sarcasm with the Italian accent.

That's what I read.

I also read a heavy "waht*EV*ar...!"

Who knows. I doubt Vale would be pedantic regarding such subjects I wanted to make sure the OP's question ("Lastly, I think I've interrupted my yeast mid mitosis; is that what I'm seeing, here?") in the first post was answered.

 

[Nate R]

All good natured (hopefully) jabs aside....

I wish i had someone make this connection for me in school... like, 'hey one day you could make your own beer!'

I would have paid much more attention!

I was never a bad student but didn't care much for biology....