Chromosome segregation inBacillus subtilis

Abstract

Bacillus subtilis, a Gram-positive bacterium commonly found in soil, is an excellent model organism for the study of basic cell processes, such as cell division and cell differentiation, called sporulation. In B. subtilis the essential genetic information is carried on a single circular chromosome, the correct segregation of which is crucial for both vegetative growth and sporulation. The proper completion of life cycle requires each daughter cell to obtain identical genetic information. The consequences of inaccurate chromosome segregation can lead to formation of anucleate cells, cells with two chromosomes, or cells with incomplete chromosomes. Although bacteria miss the classical eukaryotic mitotic apparatus, the chromosome segregation is undeniably an active process tightly connected to other cell processes as DNA replication and compaction. To fully understand the chromosome segregation, it is necessary to study this process in a wider context and to examine the role of different proteins at various cell life cycle stages. The life cycle of B. subtilis is characteristic by its specific cell differentiation process where, two slightly different segregation mechanisms exist, specialized in vegetative growth and in sporulation.

Cell Size Control in Bacteria

“…Activation of forespore specific gene expression appears to be dependent in part on the transient genetic asymmetry generated by formation of the polar septum which bisects one end of the chromosome such that only the origin-proximal ~30% region is in the forespore immediately following septation (for review see [105]). The remainder of the chromosome is later pumped into the forespore via the SpoIIIE DNA translocase [57, 106–108].…”

The Application of Imaging Flow Cytometry for Characterisation and Quantification of Bacterial Phenotypes

“…Unlike L. plantarum and P. acidilactici , B. subtilis sporulates in response to starvation and increases its cell density, whereby small, resistant, dormant endospores are produced ( Pavlendová et al., 2007 ; Tan and Ramamurthi, 2014 ), measuring 1.40 ± 0.14 µm in length and 0.55 ± 0.035 µm in diameter, as revealed by scanning transmission electron microscopy ( Leuschner and Lillford, 2000 ; Pavlendová et al., 2007 ; Tan and Ramamurthi, 2014 ). Endospores remain dormant until favourable nutrient conditions trigger their germination ( Errington and Wu, 2017 ).…”