Talk:Bacillus

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Text from a flashcard I wrote. Update article as needed. maveric149
Bacillus Flashcard

1) Gram/Catalase rxn. (E pathway)?

2) Microscopic appearance?

3) Colony characteristics?

4) Isolation & Enrichment Strategy?

5) Representitive Species (notable attributes)?

1) +/+ (O2 as TEA –– fac. anaerobes)

2) Rods w/ lobes (oval endospores)

3) Lg., spreading w/ irregular edges

4) a) Soil (shake w/ water)

b) MS agar (melted) low nutrient
c) 20°C 

5) B. cereus (food poisoner in milk)

B. subtilis (obl. aerobe; spores survive heating ; ropiness in bread)
B. coagulans (grows to pH 4.2 ; flat sour of cans) 

Info is now in article. --mav

Contents 1 Gram-stained? 2 Isolation 3 Paenbacillus 4 Bacillus sp. 5 Escherichia coli, gram negative bacillus

[edit] Gram-stained?

"A Gram stain allows one to distinguish between cocci (round) and bacilli (rod-shaped) bacteria, as well as between Gram-positive and Gram-negative bacteria (the former are stained purple, the latter red)."

Elaborate more on this to get it more accurate. Gram-staining might help to distinguish bacteria shapes, but it doesn't really have anything to do with shape does it? And "the former are stained purple, the latter red"? The Gram-negative bacterium isn't gram stained at all is it? It's completely unaffected? - Jerryseinfeld 23:59, 1 Oct 2004 (UTC)

Gram negative bacteria are stained (red) by a Gram stain. If you don't use a stain of some sort, you can't tell what shape the bacterium is, because you can't see it. The Gram-stain stains both Gram-negative and Gram-positive bacteria, but it stains them differentially.

But with an electron microscope you see the shape regardless of color don't you? - Jerryseinfeld 23:59, 1 Oct 2004 (UTC)

Well, you don't look through an electron microscope, so seeing here means what you see in looking at the photographic (or CRT) image produced by an electron microscope, and the sample has been treated in various ways prior to the microscopy to make the bacteria visible. - Nunh-huh 00:54, 2 Oct 2004 (UTC)

[1] the initial stain, crystal violet, stains both types, both Gram-positive and Gram-negative: if you stop after step one, both Gram-positive and Gram-negative bacteria are purple.

[2] Gram's iodine solution is added, fixing the crystal violet in the Gram-positive bacteria. If you look after this step, both Gram-positive and Gram-negative bacteria are still purple.

[3] The slide is then decolorized with an alcohol and actone mixture. If you look now, Gram-positive bacteria are purple, and Gram-negative are clear.

[4] Safranin is now applied: it is taken up by both Gram-positive and Gram-negative bacteria. The Gram-positive bacteria are already purple, and the safranin doesn't change the color much, but it does make the Gram-negative bacteria pink/red.

Both crystal violet and safranin are taken up by both Gram-negative and Gram-positive bacteria: the step/characteristic that allows their differentiation is the decolorization step, which removes the crystal violet from the gram-negative bacteria only (at least it does if it's done right: it's not an exact differentiation and there's some element of skill in the decolorizaiton step).

How does it work? Gram-positive cells have a much thicker outer layer of peptidoglycan than do Gram-negative. When the iodine is added to a crystal violet-stained cell, it combines to form a larger molecule that precipitates out within the cell. The decolorizing mixture causes dehydration of the multilayered peptidoglycan in the gram-positive call wall, thus decreasing the space between the molecules and causing the cell wall to trap the crystal violet-iodine complex within the cell. But in gram-negative bacteria, the decolorizing mixture acts as a lipid solvent and dissolves the outer membrane of the gram-negative cell wall. The thin layer of peptidoglycan is unable to retain the crystal violet-iodine complex and the cell is decolorized.

Too much info for here I think, though perhaps it can be added to Gram stain - Nunh-huh 22:25, 28 Sep 2004 (UTC)

You can make out cocci and bacilli through the light microscope without any staining. Gram-staining does help, but so do some other things, and I don't think it makes sense to discuss the techniques here. Josh

[edit] Isolation

Regarding this:

An easy way to isolate a Bacillus species is by placing non-sterile soil in a test tube with water, shake, place in melted mannitol salts agar, and incubate at room temperature for at least a day.

Its not that accurate, even if you dilution plate on to mannitol salts, you will get many different organisms growing. I know because I have done this, I got about 55 OTU's (operational taxonomic units) out of soil. So yep you will be some Bacillus, but lots of other species also. Onco p53 06:19, 18 Jan 2005 (UTC)

Question, does Bacillus species even grow in the high salt concentrations found on Mannitol Salts Plates? jvdimas

[edit] Paenbacillus

I noticed someone added Bacillus larvae here, but this has actually been reclassified as Paenbacillus larvae - it should now probably go under a separate entry for genus Paenbacillus, although I left it here for the moment. Any thoughts?

Change it to Paenibacillus. note the spelling. Onco p53 19:03, 17 Feb 2005 (UTC)

[edit] Bacillus sp.

I just read about something called "Bacillus sp," here: [1] There's no Wikipedia article. Should there be one? Badagnani 04:05, 25 June 2006 (UTC)

[edit] Escherichia coli, gram negative bacillus

I realize the article is about the genus bacillus, nevertheless there should be an explanation somewhere in the article that the cell morphology term is different from the genus. Bacillus in morphology context does not automatically mean gram-positive, as E. Coli proves. --—The preceding unsigned comment was added by Phange (talk • contribs).

It should be noted that the morphology of E. coli is not bacilli, but rather coccibacilli.