Manno Daniela Erminia, Talà Adelfia, Calcagnile Matteo, Resta Silvia Caterina, Alifano Pietro, Serra Antonio
Department of Mathematics and Physics "E. De Giorgi", University of Salento, Lecce, Italy.
Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy.
Res Microbiol. 2021 Sep-Oct;172(6):103865. doi: 10.1016/j.resmic.2021.103865. Epub 2021 Jul 18.
An extensive morphological analysis of the Neisseria meningitidis cell envelope, including serogroup B capsule and outer membrane, based on atomic force microscopy (AFM) together with mechanical characterization by force spectroscopic measurements, has been carried out. Three meningococcal strains were used: the encapsulated serogroup B strain B1940, and the isogenic mutants B1940 siaD(+C) (lacking capsule), and B1940 cps (lacking both capsule and lipooligosaccharide outer core). AFM experiments with the encapsulated strain B1940 provided unprecedented images of the meningococcal capsule, which seems to be characterized by protrusions ("bumps") with the lateral dimensions of about 30 nm. Measurement of the Young's modulus provided quantitative assessment of the property of the capsule to confer resistance to mechanical stress. Moreover, Raman spectroscopy gave a fingerprint by which it was possible to identify the specific molecular species of the three strains analyzed, and to highlight major differences between them.
