The Buoyancy of <italic toggle="yes">Cryptococcus neoformans</italic> Is Affected by Capsule Size

ABSTRACT Cryptococcus neoformans is an environmental pathogenic fungus with a worldwide geographical distribution that is responsible for hundreds of thousands of human cryptococcosis cases each year. During infection, the yeast undergoes a morphological transformation involving capsular enlargement...

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Autores principales:	Raghav Vij, Radames J. B. Cordero, Arturo Casadevall
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2018
Materias:	Cryptococcus neoformans buoyancy capsular polysaccharide yeast density Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/5ad06ecb83de4e24b41164d284550a42
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spelling	oai:doaj.org-article:5ad06ecb83de4e24b41164d284550a422021-11-15T15:22:21ZThe Buoyancy of <italic toggle="yes">Cryptococcus neoformans</italic> Is Affected by Capsule Size10.1128/mSphere.00534-182379-5042https://doaj.org/article/5ad06ecb83de4e24b41164d284550a422018-12-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mSphere.00534-18https://doaj.org/toc/2379-5042ABSTRACT Cryptococcus neoformans is an environmental pathogenic fungus with a worldwide geographical distribution that is responsible for hundreds of thousands of human cryptococcosis cases each year. During infection, the yeast undergoes a morphological transformation involving capsular enlargement that increases microbial volume. To understand the factors that play a role in environmental dispersal of C. neoformans and C. gattii, we evaluated the cell density of Cryptococcus using Percoll isopycnic gradients. We found differences in the cell densities of strains belonging to C. neoformans and C. gattii species complexes. The buoyancy of C. neoformans strains varied depending on growth medium. In minimal medium, the cryptococcal capsule made a major contribution to the cell density such that cells with larger capsules had lower density than those with smaller capsules. Removing the capsule, by chemical or mechanical methods, increased the C. neoformans cell density and reduced buoyancy. Melanization of the C. neoformans cell wall, which also contributes to virulence, produced a small but consistent increase in cell density. Encapsulated C. neoformans sedimented much more slowly in seawater as its density approached the density of water. Our results suggest a new function for the capsule whereby it can function as a flotation device to facilitate transport and dispersion in aqueous fluids. IMPORTANCE The buoyancy of a microbial cell is an important physical characteristic that may affect its transportability in fluids and interactions with tissues during infection. The polysaccharide capsule surrounding C. neoformans is required for infection and dissemination in the host. Our results indicate that the capsule has a significant effect on reducing cryptococcal cell density, altering its sedimentation in seawater. Modulation of microbial cell density via encapsulation may facilitate dispersal for other important encapsulated pathogens.Raghav VijRadames J. B. CorderoArturo CasadevallAmerican Society for MicrobiologyarticleCryptococcus neoformansbuoyancycapsular polysaccharideyeast densityMicrobiologyQR1-502ENmSphere, Vol 3, Iss 6 (2018)
institution	DOAJ
collection	DOAJ
language	EN
topic	Cryptococcus neoformans buoyancy capsular polysaccharide yeast density Microbiology QR1-502
spellingShingle	Cryptococcus neoformans buoyancy capsular polysaccharide yeast density Microbiology QR1-502 Raghav Vij Radames J. B. Cordero Arturo Casadevall The Buoyancy of <italic toggle="yes">Cryptococcus neoformans</italic> Is Affected by Capsule Size
description	ABSTRACT Cryptococcus neoformans is an environmental pathogenic fungus with a worldwide geographical distribution that is responsible for hundreds of thousands of human cryptococcosis cases each year. During infection, the yeast undergoes a morphological transformation involving capsular enlargement that increases microbial volume. To understand the factors that play a role in environmental dispersal of C. neoformans and C. gattii, we evaluated the cell density of Cryptococcus using Percoll isopycnic gradients. We found differences in the cell densities of strains belonging to C. neoformans and C. gattii species complexes. The buoyancy of C. neoformans strains varied depending on growth medium. In minimal medium, the cryptococcal capsule made a major contribution to the cell density such that cells with larger capsules had lower density than those with smaller capsules. Removing the capsule, by chemical or mechanical methods, increased the C. neoformans cell density and reduced buoyancy. Melanization of the C. neoformans cell wall, which also contributes to virulence, produced a small but consistent increase in cell density. Encapsulated C. neoformans sedimented much more slowly in seawater as its density approached the density of water. Our results suggest a new function for the capsule whereby it can function as a flotation device to facilitate transport and dispersion in aqueous fluids. IMPORTANCE The buoyancy of a microbial cell is an important physical characteristic that may affect its transportability in fluids and interactions with tissues during infection. The polysaccharide capsule surrounding C. neoformans is required for infection and dissemination in the host. Our results indicate that the capsule has a significant effect on reducing cryptococcal cell density, altering its sedimentation in seawater. Modulation of microbial cell density via encapsulation may facilitate dispersal for other important encapsulated pathogens.
format	article
author	Raghav Vij Radames J. B. Cordero Arturo Casadevall
author_facet	Raghav Vij Radames J. B. Cordero Arturo Casadevall
author_sort	Raghav Vij
title	The Buoyancy of <italic toggle="yes">Cryptococcus neoformans</italic> Is Affected by Capsule Size
title_short	The Buoyancy of <italic toggle="yes">Cryptococcus neoformans</italic> Is Affected by Capsule Size
title_full	The Buoyancy of <italic toggle="yes">Cryptococcus neoformans</italic> Is Affected by Capsule Size
title_fullStr	The Buoyancy of <italic toggle="yes">Cryptococcus neoformans</italic> Is Affected by Capsule Size
title_full_unstemmed	The Buoyancy of <italic toggle="yes">Cryptococcus neoformans</italic> Is Affected by Capsule Size
title_sort	buoyancy of <italic toggle="yes">cryptococcus neoformans</italic> is affected by capsule size
publisher	American Society for Microbiology
publishDate	2018
url	https://doaj.org/article/5ad06ecb83de4e24b41164d284550a42
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The Buoyancy of <italic toggle="yes">Cryptococcus neoformans</italic> Is Affected by Capsule Size

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