Hexagonal surface layer of Campylobacter fetus isolated from humans

Area of Science:

• Microbiology
• Cell Biology
• Electron Microscopy

Background:

• Campylobacter fetus is a bacterial species known for causing various infections.
• The surface structure of bacteria plays a crucial role in their interaction with the host environment.
• S layers are outermost proteinaceous envelopes found in many prokaryotes, often involved in cell protection and adhesion.

Purpose of the Study:

• To investigate the surface structure of Campylobacter fetus using advanced electron microscopy techniques.
• To characterize the different types of S layers present in Campylobacter fetus.
• To understand the dynamics of S layer expression in relation to cultivation methods.

Main Methods:

• Utilizing freeze-etching electron microscopy to visualize the surface ultrastructure of Campylobacter fetus.
• Cultivating high-passage-number strains of Campylobacter fetus on standard culture media.
• Inoculating Campylobacter fetus strains into a host model to observe S layer recovery after animal passage.

Main Results:

• Electron microscopy revealed two distinct types of S layers on the surface of Campylobacter fetus: one arranged in a hexagonal array and another in a tetragonal array.
• High-passage-number strains of Campylobacter fetus exhibited a loss of their S layer when cultured extensively on artificial media.
• The lost S layer was observed to be re-expressed by the bacteria after a single passage through an animal host.

Conclusions:

• Campylobacter fetus possesses structurally diverse S layers, with hexagonal and tetragonal arrays being identified.
• The expression of S layers in Campylobacter fetus is sensitive to laboratory cultivation conditions, leading to S layer loss.
• In vivo conditions, such as animal passage, can induce the re-expression of S layers, highlighting the adaptability of Campylobacter fetus.