Molecular Basis and Ecological Relevance of <italic toggle="yes">Caulobacter</italic> Cell Filamentation in Freshwater Habitats

ABSTRACT All living cells are characterized by certain cell shapes and sizes. Many bacteria can change these properties depending on the growth conditions. The underlying mechanisms and the ecological relevance of changing cell shape and size remain unclear in most cases. One bacterium that undergoe...

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Autores principales:	Kristina Heinrich, David J. Leslie, Michaela Morlock, Stefan Bertilsson, Kristina Jonas
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2019
Materias:	Caulobacter crescentus biofilms cell cycle cell shape environmental signals freshwater habitats Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/cfb2966d9c834896b788058e86e07dd2
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spelling	oai:doaj.org-article:cfb2966d9c834896b788058e86e07dd22021-11-15T16:22:10ZMolecular Basis and Ecological Relevance of <italic toggle="yes">Caulobacter</italic> Cell Filamentation in Freshwater Habitats10.1128/mBio.01557-192150-7511https://doaj.org/article/cfb2966d9c834896b788058e86e07dd22019-08-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.01557-19https://doaj.org/toc/2150-7511ABSTRACT All living cells are characterized by certain cell shapes and sizes. Many bacteria can change these properties depending on the growth conditions. The underlying mechanisms and the ecological relevance of changing cell shape and size remain unclear in most cases. One bacterium that undergoes extensive shape-shifting in response to changing growth conditions is the freshwater bacterium Caulobacter crescentus. When incubated for an extended time in stationary phase, a subpopulation of C. crescentus forms viable filamentous cells with a helical shape. Here, we demonstrated that this stationary-phase-induced filamentation results from downregulation of most critical cell cycle regulators and a consequent block of DNA replication and cell division while cell growth and metabolism continue. Our data indicate that this response is triggered by a combination of three stresses caused by prolonged growth in complex medium, namely, the depletion of phosphate, alkaline pH, and an excess of ammonium. We found that these conditions are experienced in the summer months during algal blooms near the surface in freshwater lakes, a natural habitat of C. crescentus, suggesting that filamentous growth is a common response of C. crescentus to its environment. Finally, we demonstrate that when grown in a biofilm, the filamentous cells can reach beyond the surface of the biofilm and potentially access nutrients or release progeny. Altogether, our work highlights the ability of bacteria to alter their morphology and suggests how this behavior might enable adaptation to changing environments. IMPORTANCE Many bacteria drastically change their cell size and morphology in response to changing environmental conditions. Here, we demonstrate that the freshwater bacterium Caulobacter crescentus and related species transform into filamentous cells in response to conditions that commonly occur in their natural habitat as a result of algal blooms during the warm summer months. These filamentous cells may be better able to scavenge nutrients when they grow in biofilms and to escape from protist predation during planktonic growth. Our findings suggest that seasonal changes and variations in the microbial composition of the natural habitat can have profound impact on the cell biology of individual organisms. Furthermore, our work highlights that bacteria exist in morphological and physiological states in nature that can strongly differ from those commonly studied in the laboratory.Kristina HeinrichDavid J. LeslieMichaela MorlockStefan BertilssonKristina JonasAmerican Society for MicrobiologyarticleCaulobacter crescentusbiofilmscell cyclecell shapeenvironmental signalsfreshwater habitatsMicrobiologyQR1-502ENmBio, Vol 10, Iss 4 (2019)
institution	DOAJ
collection	DOAJ
language	EN
topic	Caulobacter crescentus biofilms cell cycle cell shape environmental signals freshwater habitats Microbiology QR1-502
spellingShingle	Caulobacter crescentus biofilms cell cycle cell shape environmental signals freshwater habitats Microbiology QR1-502 Kristina Heinrich David J. Leslie Michaela Morlock Stefan Bertilsson Kristina Jonas Molecular Basis and Ecological Relevance of <italic toggle="yes">Caulobacter</italic> Cell Filamentation in Freshwater Habitats
description	ABSTRACT All living cells are characterized by certain cell shapes and sizes. Many bacteria can change these properties depending on the growth conditions. The underlying mechanisms and the ecological relevance of changing cell shape and size remain unclear in most cases. One bacterium that undergoes extensive shape-shifting in response to changing growth conditions is the freshwater bacterium Caulobacter crescentus. When incubated for an extended time in stationary phase, a subpopulation of C. crescentus forms viable filamentous cells with a helical shape. Here, we demonstrated that this stationary-phase-induced filamentation results from downregulation of most critical cell cycle regulators and a consequent block of DNA replication and cell division while cell growth and metabolism continue. Our data indicate that this response is triggered by a combination of three stresses caused by prolonged growth in complex medium, namely, the depletion of phosphate, alkaline pH, and an excess of ammonium. We found that these conditions are experienced in the summer months during algal blooms near the surface in freshwater lakes, a natural habitat of C. crescentus, suggesting that filamentous growth is a common response of C. crescentus to its environment. Finally, we demonstrate that when grown in a biofilm, the filamentous cells can reach beyond the surface of the biofilm and potentially access nutrients or release progeny. Altogether, our work highlights the ability of bacteria to alter their morphology and suggests how this behavior might enable adaptation to changing environments. IMPORTANCE Many bacteria drastically change their cell size and morphology in response to changing environmental conditions. Here, we demonstrate that the freshwater bacterium Caulobacter crescentus and related species transform into filamentous cells in response to conditions that commonly occur in their natural habitat as a result of algal blooms during the warm summer months. These filamentous cells may be better able to scavenge nutrients when they grow in biofilms and to escape from protist predation during planktonic growth. Our findings suggest that seasonal changes and variations in the microbial composition of the natural habitat can have profound impact on the cell biology of individual organisms. Furthermore, our work highlights that bacteria exist in morphological and physiological states in nature that can strongly differ from those commonly studied in the laboratory.
format	article
author	Kristina Heinrich David J. Leslie Michaela Morlock Stefan Bertilsson Kristina Jonas
author_facet	Kristina Heinrich David J. Leslie Michaela Morlock Stefan Bertilsson Kristina Jonas
author_sort	Kristina Heinrich
title	Molecular Basis and Ecological Relevance of <italic toggle="yes">Caulobacter</italic> Cell Filamentation in Freshwater Habitats
title_short	Molecular Basis and Ecological Relevance of <italic toggle="yes">Caulobacter</italic> Cell Filamentation in Freshwater Habitats
title_full	Molecular Basis and Ecological Relevance of <italic toggle="yes">Caulobacter</italic> Cell Filamentation in Freshwater Habitats
title_fullStr	Molecular Basis and Ecological Relevance of <italic toggle="yes">Caulobacter</italic> Cell Filamentation in Freshwater Habitats
title_full_unstemmed	Molecular Basis and Ecological Relevance of <italic toggle="yes">Caulobacter</italic> Cell Filamentation in Freshwater Habitats
title_sort	molecular basis and ecological relevance of <italic toggle="yes">caulobacter</italic> cell filamentation in freshwater habitats
publisher	American Society for Microbiology
publishDate	2019
url	https://doaj.org/article/cfb2966d9c834896b788058e86e07dd2
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Molecular Basis and Ecological Relevance of <italic toggle="yes">Caulobacter</italic> Cell Filamentation in Freshwater Habitats

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