Before I embarass myself further trying to describe principles of
Natural PhilosophyPhysics comprehensibly, I think I’ll do a post or two on things that I think I can more easily describe…
I will also remind everyone that I am merely an undergraduate, so if you happen to be speaking to a Ph.D. microbiologist and mention “some guy on the internet said…” and he or she tells you I’m full of it, I’d appreciate it if someone would tell me. (If they say “Wow, that guy’s a genius“, tell them I say “thanks” and ask if they’ve got any spare grant money or surplus equipment they could send me…)
I did some poking through the web server logs and noticed a few hits from search queries, looking for basic information about microbiology (and in particular, preparing and staining slides).
(I found it interesting that although most of the hits on this site are Mozilla Firefox, every single one of the search-engine-query hits were using Microsoft Internet Explorer. [Safari looks like it amounts to a little more than the number of MSIE hits.] Don’t know if it MEANS anything, but still interesting.)
Aside from a hit from someone looking for pictures of Gram-stained bacteria and, oddly, one person looking for information about the “No You Can’t Have (X), Not Yours” meme, here are the queries that have led to my page so far:
From somewhere in Kuwait: someone looking for “Gram (something) that stain red because”
From Toronto, Canada: “Gram Staining work”
Hopefully, I managed to explain whatever they were looking for back in my post about why the Gram Stain works.
The “Purpose of Heat-Fixing Bacteria on a Slide” query (posted about here) came from somewhere at a major technology company in Texas (and, coincidentally, today from someone at a college in Florida). And for Norfolk, Virginia (who just reached the site as I was typing this) – “Fixing” just means to keep something from moving – in this case, it means making the bacteria “stick” to the slide. Though I suspect he or she already figured that out from the previous “heat-fixing” post. On a related note, someone at a community college in Texas wanted to know “what would happen if too much heat were applied in heat-fixing”. To answer that one is (to the best of my knowledge), that it depends on how much is “too much”. Comparatively fragile bacteria like Mycobacteria would, I assume, tend to fall apart in the heat relatively easily. A bit more heat would probably fry the Gram-negative type bacteria, and a little more would finally destroy the Gram-positives (don’t quote me on this, I’m guessing here). One trick I’ve picked up is to hold the slide with my bare fingers (on the edges of the slide as far from the smear as possible) and slowly pass the slide into and out of the Bunsen burner flame until the slide gets uncomfortably hot (but stopping before it starts actually burning my fingers). That seems to do the job reasonably well.
Someone from the Fresno, California area wanted to find out how negative staining works.
A “Negative” stain is like a “negative” of a photograph – you’re staining everything BUT the bacteria on the slide (ideally). This is useful if something about the bacteria you’re looking at keeps it from being easily stained, or in particular if you want to see if the bacteria produces a capsule. If you stain the slide with India Ink, it’ll make the slide itself black, but leave a clear spot where the encapsulated (or, conceivably, any other bacteria that won’t soak up the ink) are, so you can find them. They also apparently do something similar in some kinds of electron microscopy.
Someone in New Jersey wanted to know what the purpose of “Simple Stains” were. A “Simple” stain just means you’re putting one kind of dye on the slide to color the bacteria, and you don’t really care about the color. Unlike differential stains (like the Gram stain) or a diagnostic stain (like an Endospore stain), it doesn’t really tell you anything about the bacteria other than what you can directly see in the microscope – but if the relative size, shape, and arrangement of the bacteria is all you’re interested in, a simple stain may be all you need. It doesn’t matter too much what kind of dye you use for this – I know methylene blue is a common one for this kind of thing.
Someone at a facility in Wyoming was trying to figure out what an alcohol wash did to bacterial cell walls. Presumably he got directed to this site because of my Gram Stain post. It’s probably worth mentioning that I believe the alcohol wash doesn’t actually do much to the cell wall – but it does seem to remove the outer membrane that is outside of the cell wall, if the bacteria have one.
Someone in the Chicago, Illinois area appeared to be searching for general information on choosing a dye for staining – that one probably deserves a post of its own, but I’ll try to put something together on it.
Another query was someone from the Phillipines specifically looking for an article on Schizomycetes. I just notices something about that post – I actually forgot to add one useful note about “Fission Fungi”: That’s what “Schizomycete” actually means (Greek: Schizo-: split in two -mycetes: relating to fungus). Also, for those photosynthetic bacteria (“Fission Algae”) the contemporary term was “Schizophyte”.
Finally, I find myself intensely curious about the very focussed query originating from a healthcare product company in New York, looking for information about Gram Staining of Bacillus atropheaus, specifically. Maybe Willy Bacillus has found his first fan…