www.lesswrong.com/posts/FijbeqdovkgAusGgz/grey-goo-is-unlikely
1 correction found
Iron is the active catalytic site of many enzymes, and is needed by all known life.
This is incorrect: at least some bacteria can grow without requiring iron (e.g., Borrelia burgdorferi), contradicting the claim that iron is needed by all known life.
Full reasoning
The post claims that iron is required by all known life.
However, peer‑reviewed literature documents exceptions:
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Borrelia burgdorferi (Lyme disease spirochete) can eliminate the need for iron.
- Posey & Gherardini (Science, 2000) report that B. burgdorferi “has bypassed this host defense by eliminating the need for iron,” and that it “grew normally” even with iron chelators, indicating no iron requirement for growth.
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Some lactobacilli show no growth stimulation from iron and are described as not needing iron added to growth media.
- Imbert & Blondeau (Current Microbiology, 1998) tested multiple Lactobacillus strains in defined media and found no significant growth stimulation from iron additions; they conclude this supports an “absolute manganese requirement” and the “needless incorporation of iron in growth media.”
Because credible primary sources show organisms that can grow without iron requirement, the statement that iron “is needed by all known life” is contradicted by evidence and is therefore factually wrong.
2 sources
- Lack of a role for iron in the Lyme disease pathogen (Science, 2000) - PubMed
Abstract notes Borrelia burgdorferi “eliminat[ed] the need for iron” and “grew normally” with iron chelators.
- On the iron requirement of lactobacilli grown in chemically defined medium (Curr Microbiol, 1998) - PubMed
Reports no significant growth stimulation from iron; concludes “needless incorporation of iron in growth media” and emphasizes manganese requirement.