Extremely slow pace of life in deep-sea bacteria

The pace of life of organisms tends to be limited where basic resources are scarce. In some environments this is taken to extremes.
 
The Pacific Ocean, being so vast and far-removed from any alluvial input or upwelling, can be thought of as a marine desert. The central Pacific Ocean is poorly productive despite the abundance of water and energy, and because of the water is nutrient-poor.
 
See Roy H et al.. (2012), Science vol. 336, issue 6083, pages 922-925 (http://science.sciencemag.org/content/336/6083/922).

This study adds a remarkable dimension to the extreme nutrient-poverty of the Pacific. This is because it takes observation down not only to the sea bed, but 30 m below the sea bed. What we are talking about are extremely nutrient-poor substrates that have experienced no renewal/rejuvenation/increment for the last 86 million years.
 
Furthermore, the environment is cold and oxygen-poor.

In these deep sediments, the only forms of life are bacteria and unicellular Archaea, in vanishingly small numbers. There are only one thousand of these tiny cells in a whole cubic cm of sediment.
 
These cells respire oxygen 10,000-fold more slowly than do laboratory cultures of bacteria. The authors think that the community is so sparse, and the metabolic rates so limited, that the concentrations of nutrients probably represent the bare minimum required to keep cellular enzymes and DNA working.
 
The author, Hans Roy, states “It looks like we have reached the absolute power limit for the metabolism of cells”.
 
A similar study, closer to Japan, can be found by Yuki Morono in Proc. National Academy of Sciences.

Morono reported that, at first encounter, the cells seemed dead. When he fed them glucose and nutrients, most of the cells absorbed some food, revealing their survival. Morono surmises that his cells may be thousands of years old. This is because, at their rate of metabolism, it would take each cell hundreds of thousands of years to generate enough energy to replicate.
 
In summary:
Here we have, in response to an extreme desert in terms of resources, what seem to be the organisms with the slowest pace of life ever recorded. And this greatly extends the known range in this parameter, i.e. pace of life.

Posted on 08 de julho de 2022, 05:52 AM by milewski