Pigmentation and Sporulation Are Alternative Cell Fates in Bacillus pumilus SF214

Riccardo Manganelli,Nicola Manzo,Ezio Ricca,Blanda Di Luccia,Rachele Isticato,Enrica D’Apuzzo,Maurilio De Felice

doi:10.1371/journal.pone.0062093

Riccardo Manganelli, Nicola Manzo + Show 5 more

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https://doi.org/10.1371/journal.pone.0062093

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Journal: PloS one	Publication Date: Apr 25, 2013
Citations: 47	License type: CC BY 4.0

Affiliation: Federico II University Hospital

Abstract

Bacillus pumilus SF214 is a spore forming bacterium, isolated from a marine sample, able to produce a matrix and a orange-red, water soluble pigment. Pigmentation is strictly regulated and high pigment production was observed during the late stationary growth phase in a minimal medium and at growth temperatures lower than the optimum. Only a subpopulation of stationary phase cells produced the pigment, indicating that the stationary culture contains a heterogeneous cell population and that pigment synthesis is a bimodal phenomenon. The fraction of cells producing the pigment varied in the different growth conditions and occured only in cells not devoted to sporulation. Only some of the pigmented cells were also able to produce a matrix. Pigment and matrix production in SF214 appear then as two developmental fates both alternative to sporulation. Since the pigment had an essential role in the cell resistance to oxidative stress conditions, we propose that within the heterogeneous population different survival strategies can be followed by the different cells.

Highlights

Spore-forming Bacilli are Gram positive organisms characterized by the ability to differentiate the endospore, a metabolically quiescent and extremely resistant cell type
We report that in SF214 pigment production is a highly regulated process that occurs during the stationary growth phase only in cells not devoted to spore formation
Synthesis of the water-soluble pigment produced by SF214 is a strictly regulated process as it depends on the growth-phase, -temperature and -medium

Summary

Introduction

Spore-forming Bacilli are Gram positive organisms characterized by the ability to differentiate the endospore (spore), a metabolically quiescent and extremely resistant cell type. The soil is generally indicated as the main habitat of Bacilli, spores have been found in many diverse environments, including rocks, dust, aquatic environments, and the gut of various insects and animals [1,2] Such a wide environmental distribution is facilitated by the spore ability to survive long-term absence of water and nutrients and withstand extreme habitats that would kill other cell types [3]. An innermost layer is the peptidoglycan-rich cortex that is itself surrounded by additional layers of proteinaceous material, the coat and, in some species, the exosporium [4,5] Together these components protect the spore from UV radiation, extremes of heat or pH, exposure to solvents, hydrogen peroxide, toxic chemicals and lytic enzymes [3,6]. In the presence of water and appropriate nutrients the spore starts germination, a fast process during which the protective structures are removed and resumption of vegetative cell growth is allowed [3,4]

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