Clocks, Anticipation, and Growth in Bacteria

Circadian rhythms are widespread across all kingdoms of life, and they are frequently assumed to provide an adaptive benefit by allowing organisms to anticipate diel cycles in their environment. Yet it has proven extremely difficult to determine precisely how such anticipation confers a fitness advantage. Here, we use mathematical modeling to address this question for nitrogen-fixing cyanobacteria.¹ By extending recent work on growth laws in E. coli,² we show that it is difficult to change the composition of the proteome when the growth rate is small, and thus that the average growth rate can be increased by using a clock to anticipate the onset of darkness by switching to a dark-adapted proteome late in the day, when growth rates are still large.

¹ M. Monti, D.K. Lubensky, and P.R. ten Wolde, arXiv:1805.04538.
² D.W. Erickson et al., Nature 551, 119-23 (2017).