Expert: Florence M Rollwagen - 5/16/2008

Question
QUESTION: Hi:

I am looking for any type of bacterium that fits all the following categories:

1. Obligate-anaerobe
2. Gram-negative
3. Non-pathogenic
4. Non-parasitic
5. Produces sulfur-containing organic compounds [such as thiols]
6. Is attracted to sulfur-contain organic compounds

Please note that this is not a homework question. It is a question of my own personal interest.

If there is no such bacterium that fits all completely, then which bacterium gets the closest?


Thanks,

Green

ANSWER: Hi Green:

First, I have two questions for you:

1.  What does "attracted to sulfur-containing organic compounds" mean
2.  Is it hyperthermophilic or extremophilic?

Right now, I suspect a chemolithotroph from deep sea vents.
These organisms can't be pathogenic or parasitic because they don't grow under mammalian body conditions.  They do use sulfur as the final electron acceptor in the ETC, but without knowing more tests, can't be sure.  The actual genus and species will be much more difficult to determine without genetic testing.

Here's a good website:
http://www.botos.com/marine/vents01.html
(if you're not in the 7-10th grade, apologies)

Hope this helps, write back if you have more questions.

FM Rollwagen, PhD



---------- FOLLOW-UP ----------

QUESTION: Thanks for your response.

To answer your questions:

1. "Attracted to sulfur-containing organic compounds" means is thrives in locations rich in sulfur compounds that contain carbon and hydrogen in their chemical formulae. Thiols are an example of such compounds

2. It can be hyperthermophilic/extremophilic, though I don't specifically require that it be.

I am thinking of certain bacteria that might [or might not] already present in our colons and skins [i.e. our natural florae] but don't invade our bodies or cause harm. I would also think that some of them are responsible for the aromas of aged cheeses. I could be wrong though.

Answer
AHA!   More information.

So when we consider the normal flora of the body, we have more to go on.  Normal body flora can't be extremophiles, since we aren't.  Lactobacillus and Bifidobacteria are normal flora of the gut and vagina, and also part of yogurt and cheese bacteria.  If not anaerobes, they are certainly facultative anaerobes.

Thiol requring strep, obligate anaerobes,
http://gsbs.utmb.edu/microbook/ch013.htm

Brevibacterium epidermidis produce methane thiol and isovaleric acid.  Some of this genus also are in Limburger cheese. The Brevibacteria help make the skin of this cheese. The methane thiol contributed by the Brevibacteria improve the flavors of many cheeses.

If, however, you're thinking of the sulfur smell of gas, that's another organism altogether.  Methanogenic bacteria feed on undigested starches in the colon (e.g., beans) and produce sulfur smell.  Don’t have anything to do with cheeses though.

Is this more along what you're thinking?

FM Rollwagen, PhD