Slow metabolism = long life

Image: Researcher Hans Roy opening a core sample, photo by Bo Barker Jørgensen, © Science / AAAS

I was amazed to find out that there are bacteria in the ocean floor that have metabolisms roughly 10,000 times slower than those living at the surface of the seabed. This extremely slow lifestyle may allow them to live very long lives. In fact, these microbes were found in a core sample of clay collected up to 20 meters beneath the seafloor of the North Pacific Gyre, just north of Hawaii. This depth means that the microbes settled on the ocean floor about 86 million years ago! While these as yet unidentified microbes rely on oxygen for survival, very little nutrients are available due to the large ocean currents in this area. Therefore, researchers have suggested they are still persisting off of food that arrived during the time of the dinosaurs.

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Roy H, Kallmeyer J, Adhikari RR, Pockalny R, Jorgensen BB, D'Hondt S. Aerobic Microbial Respiration in 86-Million-Year-Old Deep-Sea Red Clay. Science 18 May 2012:
Vol. 336 no. 6083 pp. 922-925.

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I take objection to your title. Slow metabolisms are certainly a correlate of high longevity, but the relationship between the two is not so simple. The classic model system of this relationship is the evolution longevity in flighted birds - birds have fast metabolisms, yet have very high maximum longevities for their body mass (which also correlates strongly with longevity, so is commonly corrected for in longevity models).

If this post seems a bit of pedantic squawk: the evolution of longevity was the topic of my MSc thesis. I get twitchy about it. True fact: I invested more time in that thesis than most new parents have invested in their newborn baby.

By BrokenDrum (not verified) on 18 May 2012 #permalink

BrokenDrum -

Good point and not at all pedantic.

As for the "lifespan" of individual bacteria, I am curious how that would normally be measured. Bacteria are haploid and directly reproduce by mitosis. An individual bacterium is unique at any given time, of course, but how the lifespan of an entity that reproduces by cloning itself is to be stated is an intriguing question. After a division, which cell is to be assigned the designation "original", and on what basis?

Also, for bacteria and microbes that can form "spores", long survival of non-reproducing individual cells at very low/near zero metabolism is quite common, here on the surface of the earth.

I hope that I don't sound pedantic - cool topic, but the treatment is a bit superficial.

Interesting finding, poor reporting.

By Mike Mellor (not verified) on 20 May 2012 #permalink

live for thousands of years?