Colpidium and bacteria galore. Interesting Spirillum

Charles Krebs · Post by **Charles Krebs** » Mon May 28, 2007 10:50 pm

I had some pond samples that were not really productive anymore, so I put a small piece of dog biscuit in each tray. Whoa!... in a couple days the water was loaded with all sorts of bacteria and a huge number of Colpidium.

Here are a few shots of some very frenzied feeding.
Take a look at the tight "crop" of a spirillum bacterium that I added to the bottom of the lower shot. It shows something I have rarely been able to observe on bacteria using my "light" microscope... a flagellum. Pretty healthy sized bacteria!
(and Ken, I even got an amoeba for you in one of the shots

)

40/0.90 Olympus, Canon 350D, DIC with electronic flash

100/1.40 Olympus, Canon 350D, DIC with electronic flash

100/1.40 Olympus, Canon 350D, DIC with electronic flash.
lower crop: 40/0.90 Olympus, Canon 350D, DIC with electronic flash

Gyrosigma · Post by **Gyrosigma** » Tue May 29, 2007 5:43 am

Amazing... (as usual...)
I did not know that bacterias have flagellum !!!
Are you sure about your text... ist it a crop from a x40 picture ???
I know that The NA of your planapo is good (0,90) but I didn't imagine that it was possible to see something like that with a x40....

your the best

best regards

Dominique

Charles Krebs · Post by **Charles Krebs** » Tue May 29, 2007 8:19 am

Dominique,

Some do and some do not. They are obviously best seen with an electron microscope. Normally they are too small to be seen with a light microscope, although I have just barely seen it once or twice with phase contrast.

As you can see from the scale, this is a pretty good size bacteria species. (I figure the specimen shown is about 1.5micron in diameter). This was a crop from a frame taken with the 40X S Plan Apo. I tried to get some with the 100X but the conditions were not as good (nearness of subject to cover slip) so the 40X shot was actually better. Since the NA of my DIC condenser is 0.90, there is only a small resolution advantage to using the 100X in DIC. The (theoretical) best resolution I should be able to get with the 40X and my setup is .37 micron, and this flagellum is probably getting pretty close to that. So the position of the subject becomes very important since resolution will suffer unless it is just right.

discomorphella · Post by **discomorphella** » Tue May 29, 2007 9:44 am

Hi Charlie--

Great shots as usual. And I completely agree, with a wet mount of uncertain thickness my 0.95 NA 60X can outperform the 100X/1.4 since it has a variable correction collar, as does your SPlanApo 40. The 1.4 NA oil objective is not able to compensate for the refraction-induced spherical aberration (water = 1.33, coverglass = 1.52 or so) and the 40X can beat it when you get the collar set correctly. The collar effectively lets you look deeper into the wet mount than the higher NA oil objective can.

--David

p.s. I usually spike my cultures with a bit of powdered milk or yeast extract, I will have to try dog biscuits now too....

olivier barth · Post by **olivier barth** » Sat Jun 02, 2007 1:42 am

hi everybody,
I'm a new member,and I apologize for my bad english.
2 years ago I took a picture of a spirilum with flagella using 40X phase contrast.
best regards.

beetleman · Post by **beetleman** » Sat Jun 09, 2007 1:50 pm

Boy, I would love to see Charles get his hands on a SEM. Maybe when they come down in price.

. Excellent photos Charles

Charles Krebs · Post by **Charles Krebs** » Fri Jun 29, 2007 6:19 pm

Oliver...
That's a good capture. The one I have posted also had a flagellum at each end, but I never did get a frame where both could be seen at the same time.