Moselio Schaechter


  • The purpose of this blog is to share my appreciation for the width and depth of the microbial activities on this planet. I will emphasize the unusual and the unexpected phenomena for which I have a special fascination... (more)

    For the memoirs of my first 21 years of life, click here.

Associate Bloggers



  • (Click photo for more information.)

Bloggers Emeriti


  • (Click photo for more information.)

Meetings & Sponsors



« Oddly Microbial: Programmed Cell Death | Main | Mycorrhizal Fungi: The World’s Biggest Drinking Straws And Largest Unseen Communication System »

August 19, 2013

A Whiff of Taxonomy – Archaeoglobus fulgidus

by Elio

Figure1
Cells of A. fulgidus are typically irregular and with a dimple. Bar: 0.5 µm. Source.

Pick an archaeon, any archaeon, and you will find it has a story to tell. Not all archaea are exotic but plenty of them are. These stalwarts live in environments we humans call extreme, where they carry out what to us seem extreme types of metabolic conversions. Most have come rather late into our awareness. To redress their neglect, I picked one almost at random. It’s a hyperthermophile called Archaeoglobus fulgidus (the genus name derives from “ancient sphere,” the species from “shining,” for its UV fluorescent glow under 420 nm light). The genus was proposed by Stetter in 1988.

The family to which this species belongs, the Archaeoglobales, is typically hyperthermophilic. A. fulgidus grows optimally at 83 °C and is at home in hellish environments such as deep sea vents, oil deposits, and hot springs. A chemolithoautotroph, it reduces sulfate to sulfide, specifically to iron sulfide when given steel pipes to 'eat'. Since iron sulfide corrodes metal pipes, it is a nuisance to the humans tapping oil deposits to produce oil and gas. On the other hand, this skill may come in handy for detoxifying metal contaminants at high temperatures.

This organism is related to archaeal methanogens such as Methanococcus, as well as Thermococcus. A. fulgidus has most of the genes for methanogenesis but lack the needed methyl-CoA reductase. So if it makes methane (which it does in small amounts), it doesn’t do it in the way of most methanogens. Its genome is relatively small, 2,178,400 base pairs, with 2,486 predicted protein coding genes. A. fulgidus is one of the better studied Archaea. Entering its name in PubMed (a questionable metric) yields 526 hits.

Now, what distinguishes A. fulgidus? Not unique among prokaryotes but well developed in this species is its ability to reduce perchlorate, an oxidant used in rocket propellants. Perchlorate is also highly toxic and a significant persistent pollutant. In the USA, contamination stemming from rocket testing now poses health risks to some people in at least 43 states. The bacteria that metabolize perchlorate have an enzyme, chlorite dismutase, which detoxifies the chlorite produced. A. fulgidus lacks that enzyme and appears to be the only prokaryote so far that can reduce perchlorate without it. Presumably, in its environment chlorite is reduced by abiotic processes. Not to sound like an archaeal chauvinist, here is also a recent paper on the decomposition of perchlorate by bacteria.

Such processes may have been important long before people made perchlorate because this compound is formed naturally. So, perchlorate metabolism may have evolved quite early and possibly in ways that differed between mesophilic bacteria and a thermophilic archaeon. These organisms may have helped detoxify the early world, for all we know. And now our activities have provided yet more work for them to do. From the point of view of A. fulgidus, our donation of perchlorate to the environment may not be pollution but perhaps a return to the good old days.

ResearchBlogging.org



Carlström CI, Wang O, Melnyk RA, Bauer S, Lee J, Engelbrektson A, & Coates JD (2013). Physiological and genetic description of dissimilatory perchlorate reduction by the novel marine bacterium Arcobacter sp. strain CAB. mBio, 4 (3) PMID: 23695836

Comments

Very interesting organism.
It would be nice to read again posts about random archaea, since these organisms are wonderful in their weirdness.

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Working...
Your comment could not be posted. Error type:
Your comment has been saved. Comments are moderated and will not appear until approved by the author. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.

Working...

Post a comment

Comments are moderated, and will not appear until the author has approved them.

Teachers' Corner

Podcast

How to Interact with This Blog

  • We welcome readers to answer queries and comment on our musings. To leave a comment or view others, remarks, click the "Comments" link in red following each blog post. We also occasionally publish guest blog posts from microbiologists, students, and others with a relevant story to share. If you are interested in authoring an article, please email us at elios179 at gmail dot com.

Subscribe via email

Translate




Search




MicrobeWorld News

Membership