Polyphosphate Storage during Sporulation in the Gram-Negative Bacterium Acetonema longum
Abstract
Using electron cryotomography, we show that the Gram-negative sporulating bacterium Acetonema longum synthesizes high-density storage granules at the leading edges of engulfing membranes. The granules appear in the prespore and increase in size and number as engulfment proceeds. Typically, a cluster of 8 to 12 storage granules closely associates with the inner spore membrane and ultimately accounts for ∼7% of the total volume in mature spores. Energy-dispersive X-ray spectroscopy (EDX) analyses show that the granules contain high levels of phosphorus, oxygen, and magnesium and therefore are likely composed of polyphosphate (poly-P). Unlike the Gram-positive Bacilli and Clostridia, A. longum spores retain their outer spore membrane upon germination. To explore the possibility that the granules in A. longum may be involved in this unique process, we imaged purified Bacillus cereus, Bacillus thuringiensis, Bacillus subtilis, and Clostridium sporogenes spores. Even though B. cereus and B. thuringiensis contain the ppk and ppx genes, none of the spores from Gram-positive bacteria had granules. We speculate that poly-P in A. longum may provide either the energy or phosphate metabolites needed for outgrowth while retaining an outer membrane.
Additional Information
© 2013 American Society for Microbiology. Received 16 June 2013 Accepted 20 June 2013; Published ahead of print 28 June 2013. We acknowledge the use of electron microscopy facilities at the UCLA Electron Imaging Center for NanoMachines at the California NanoSystems Institute (CNSI) and thank Ivo Atanasov and Dan Taso for technical assistance with EDX data collection and analysis. We thank Yunbin Guan and John Eiler for assistance with the NanoSIMS measurements. We thank Adrian Ponce for providing the C. sporogenes spores. The NanoSIMS apparatus is housed within the Caltech Microanalysis Center and is partially funded by the Gordon and Betty Moore Foundation. This work was funded in part by the Howard Hughes Medical Institute, the Caltech Center for Environmental Microbial Interactions, and gifts to Caltech from the Gordon and Betty Moore Foundation. This work was partially performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.Attached Files
Published - J._Bacteriol.-2013-Tocheva-3940-6.pdf
Supplemental Material - zjb999092761so1.pdf
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Additional details
- PMCID
- PMC3754598
- Eprint ID
- 41193
- Resolver ID
- CaltechAUTHORS:20130909-141442695
- Gordon and Betty Moore Foundation
- Howard Hughes Medical Institute (HHMI)
- Caltech Center for Environmental Microbial Interactions (CEMI)
- Department of Energy (DOE)
- DE-AC52-07NA27344
- Created
-
2013-09-16Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Caltech Center for Environmental Microbial Interactions (CEMI), Division of Geological and Planetary Sciences