MicrobeHunter.com Microscopy Forum

These are some pictures of Wallemia Sebi. It is a xerophile, capable of living in a hostile, low water environment, such as dried meat, salt pans, arid desert soils, high sugar or high salt foods , basically anywhere the water activity is low. There are only 3 species of Wallemia.

Great photos.. I especially like the second one, it has what appears to good DOF... Thanks for sharing..

BillT

Very nice! First time i have seen this subject!

Apochronaut, great images of a subject I knew nothing about. Thanks for the images and a chance to learn something new.

Fascinating subject (I read about it from Wikipedia). Thank you for sharing, apo.

Isn't that a perfect subject for phase contrast?

Nice detective work too. How did you identify it?

This is the first time I have ever heard of such a fungus that like dry environments (and I was a microbiologist ).

Thanks for the comments, billbilt, hkv , JimT and zzffnn. Partly , I was trying out a new option I chose for a tube lens with my older Reichert infinity D.I.N. objectives. I seem to have solved a good measure of the lateral C.A. I was running into. I just happened across this sample of W.S. in the bottom of an old maple syrup bottle that was left at the farm, when we had the fire some years ago. It's had quite a while to incubate. The bottle was still closed but not sealed. Hadn't looked at such, since I had acquired better microscopy equipment, so made a smear. Probably not the best subject to test a new photo system with.
Yes, Fan, possibly phase would be good but the depth of field would be less. The depth of field of DF does offer a better overall view and often better details too. Phase can be terribly flat and provide a plaster relief kind of image ; similar to DIC sometimes, with internal structures seeming to be on the surface. DF shows internal details a little more realistically and of all the microscopic systems I have used DF, unfortuantely is the most difficult to photograph faithfully. The internal details of the organism in the last picture, for instance were much more vivid and sharply defined in the live image.
I haven't put a sample under phase but will sometime. I now have a B-Minus 100x infinity corrected objective; the only magnification they made for the 34mm infinity system. AO kept records of their clients observations regarding the performance data of the various phase objectives they made( at one time , 24). By the time the infinity scopes arrived, they were down to 9, with only the 100x being retained as a B-Minus offering. They produced a chart, covering all of their objectives and the subjects that they were most suited to. I have an old one of these from the late 40's. I should scan it and try to add it as a further post.

I have had some connection to maple syrup production, in the past. This mold is the one that maple syrup producers have to be wary of. Packaging that loses a seal or remains unrefrigerated after opening will develop this species of mold because it is quite common in the air. There is even a record of a human sub-cutaneous abcess caused by it.
Maple syrup has a water availability around .87 or so, making it a very inhospitable substrate for most spoilage organisms. Wallemia sebi will easily colonize it, building a firm brown film on the surface and if left long enough will introduce off flavours and a few toxins ; Walleminol, tryptophol and UCA 1064-beta.

" They produced a chart, covering all of their objectives and the subjects that they were most suited to. I have an old one of these from the late 40's. I should scan it and try to add it as a further post."

Please do!.. I am sure it would be greatly appreciated...

BillT

Very nice images of an interesting organism. The optics combination you used really looks good!

I like the use of mixed light. Too often the usual techniques (BF, DF, etc) are used in pure isolation, as if that is the only option and you must not contaminate one with the other. Possibly true in some cases but lighting is an art, beauty is in the eye of the beholder, and maximum clarity of presentation is not always found in the rigorous application of limited and exactly repeatable technique (we all know the problems of DIC). I've noticed in my own scopes that one can spend a lot of time moving extra light sources around, shifting the condenser or moving stops, selective focus & contrast, etc., which can add substance or context to a given view that one wouldn't get just flipping phase in and out, for instance.

Good to have a maple syrup expert on hand!

billbillt wrote:" They produced a chart, covering all of their objectives and the subjects that they were most suited to. I have an old one of these from the late 40's. I should scan it and try to add it as a further post."

Please do!.. I am sure it would be greatly appreciated...

BillT

Check the new post for it.