The cell is amazingly energy efficient. Capable of trapping about 38% of the energy that it receives from sugar, it may be the most energy efficient machine on Earth.
When I was still in school, the rule-of-thumb for the human microbiome was that bacteria outnumbered human cells 10-to-1. Not so, say the authors of a new PLoS Biology paper, who re-crunched the numbers. According to their estimate, the ratio is much closer to 1-to-1.