Cumulative cell division time asymmetry in Staphyloccus aureus

Abstract

Asymmetry of cell division involving asymmetric damage segregation is shown to be linked to cellular senescence in bacteria. According to the current mainstream thinking, the asymmetry is observed along the old and new pole cells, wherein old pole cells accumulate damage and eventually succumb to senescence, while giving rise to fresh new pole cells at every division. If the old pole-new pole axis is central to cell division asymmetry, and thereby aging, it would be interesting to see whether cumulative cell division asymmetry is seen in spherical organisms such as Staphylococci that change the plane of division at every cycle and therefore may not have polarity. We show here that in growing microcolonies of Staphylococuus aureus, two daughter cells produced by one cell division show difference in the time taken for further division. This asymmetry is cumulative, giving rise to a frequency distribution of asymmetry which is significantly different from the distribution expected by stochastic asymmetry. Demonstration of cumulative cell division asymmetry in S. aureus suggests that functional asymmetry in cell division can exist independent of the old pole-new pole axis.