Magnesium Modulates Bacillus subtilis Cell Division Frequency. Academic Article uri icon

abstract

  • By chance, we discovered a window of extracellular magnesium (Mg2+) availability that modulates the division frequency of Bacillus subtilis without affecting its growth rate. In this window, cells grown with excess Mg2+ produce shorter cells than do those grown in unsupplemented medium. The Mg2+-responsive adjustment in cell length occurs in both rich and minimal media as well as in domesticated and undomesticated strains. Of other divalent cations tested, manganese (Mn2+) and zinc (Zn2+) also resulted in cell shortening, but this occurred only at concentrations that affected growth. Cell length decreased proportionally with increasing Mg2+ from 0.2mM to 4.0mM, with little or no detectable change being observed in labile, intracellular Mg2+, based on a riboswitch reporter. Cells grown in excess Mg2+ had fewer nucleoids and possessed more FtsZ-rings per unit cell length, consistent with the increased division frequency. Remarkably, when shifting cells from unsupplemented to supplemented medium, more than half of the cell length decrease occurred in the first 10min, consistent with rapid division onset. Relative to unsupplemented cells, cells growing at steady-state with excess Mg2+ showed an enhanced expression of a large number of SigB-regulated genes and the activation of the Fur, MntR, and Zur regulons. Thus, by manipulating the availability of one nutrient, we were able to uncouple the growth rate from the division frequency and identify transcriptional changes that suggest that cell division is accompanied by the general stress response and an enhanced demand to sequester and/or increase the uptake of iron, Mn2+, and Zn2+. IMPORTANCE The signals that cells use to trigger cell division are unknown. Although division is often considered intrinsic to the cell cycle, microorganisms can continue to grow and repeat rounds of DNA replication without dividing, indicating that cycles of division can be skipped. Here, we show that by manipulating a single nutrient, namely, Mg2+, cell division can be uncoupled from the growth rate. This finding can be applied to investigate the nature of the cell division signal(s).

published proceedings

  • J Bacteriol

altmetric score

  • 8.05

author list (cited authors)

  • Guo, T., & Herman, J. K.

citation count

  • 2

complete list of authors

  • Guo, Tingfeng||Herman, Jennifer K

editor list (cited editors)

  • Henkin, T. M.

publication date

  • January 2023