Editorial: The many wonders of the bacterial cell surface

Abstract

The microbial world offers constant reminders of the astonishing and exquisite complexity of unicellular life. The bacterial cell envelope is a remarkable example of a multifunctional and multi-faceted structure designed to protect both the integrity of the cell and dictate its shape. It insulates the intracellular compartment from the outside world but still preserves a phenomenal ability to communicate and sense the extracellular environment and exerts control of molecular trafficking of a vast array of nutrients and macromolecules. A virtual issue proposed by FEMS Microbiology Reviews, and entitled ‘Bacterial Cell Surfaces’, provides an exciting flight over the principle features of the composition, flexibility and function of the bacterial cell envelope. Glycerophospholipids represent a basic constituent of all membranes. They form the membrane bilayer that immediately surrounds the bacterial cytoplasmic compartment, as well as the inner leaflet of the Gram-negative outer membrane. While it has long been believed that the membrane composition is relatively fixed, Sohlenkamp and Geiger present a remarkable illustration of the variability of phospholipid content between different species and within a single species faced with the need to adapt to changing environments (Sohlenkamp and Geiger 2015). One of the defining features of bacteria is the application of peptidoglycan (PG) to create the rigid, stress-bearing layer of the cell envelope and dictate cell shape. This is a thick multi-layered structure in Gram-positive bacteria but is predominantly single-layered in Gram-negative bacteria, which have the added protection afforded by the outer membrane. Despite the wide distribution of PG, a few controversial exceptions have remained where this macromolecule could not be identified with conventional methods. Chlamydia-related bacteria provide a classic example. In their review, Jacquier and colleagues report on extraordinary advances that have finally resolved the question of whether Chlamydia-related bacteria contain PG. Not only is PG present, it is also … [↵][1]* Corresponding editors. E-mail: a.filloux{at}imperial.ac.uk and cwhitfie{at}uoguelph.ca [1]: #xref-corresp-1-1