ABSTRACT
Dividing cells of the coccoid Gram-positive bacterium
Staphylococcus aureus
undergo extremely rapid (millisecond) daughter cell separation (DCS) driven by mechanical crack propagation, a strategy that is very distinct from the gradual, enzymatically driven cell wall remodeling process that has been well described in several rod-shaped model bacteria. To determine if other bacteria, especially those in the same phylum (
Firmicutes
) or with similar coccoid shapes as
S. aureus
, might use a similar mechanically driven strategy for DCS, we used high-resolution video microscopy to examine cytokinesis in a phylogenetically wide range of species with various cell shapes and sizes. We found that fast mechanically driven DCS is rather rare in the
Firmicutes
(low G+C Gram positives), observed only in
Staphylococcus
and its closest coccoid relatives in the
Macrococcus
genus, and we did not observe this division strategy among the Gram-negative
Proteobacteria
. In contrast, several members of the high-G+C Gram-positive phylum
Actinobacteria
(
Micrococcus luteus
,
Brachybacterium faecium
,
Corynebacterium glutamicum
, and
Mycobacterium smegmatis
) with diverse shapes ranging from coccoid to rod all undergo fast mechanical DCS during cell division. Most intriguingly, similar fast mechanical DCS was also observed during the sporulation of the actinobacterium
Streptomyces venezuelae
.
IMPORTANCE
Much of our knowledge on bacterial cytokinesis comes from studying rod-shaped model organisms such as
Escherichia coli
and
Bacillus subtilis
. Less is known about variations in this process among different bacterial species. While cell division in many bacteria has been characterized to some extent genetically or biochemically, few species have been examined using video microscopy to uncover the kinetics of cytokinesis and daughter cell separation (DCS). In this work, we found that fast (millisecond) DCS is exhibited by species in two independent clades of Gram-positive bacteria and is particularly prevalent among the
Actinobacteria
, a diverse group that includes significant pathogens as well as bacteria that generate medically important antibiotics.
Bacillus thuringiensispeptidoglycan hydrolase SleB171 involved in daughter cell separation during cell division
