Researchers track how spores break out of dormant state

June 4, 2007

Tapping into the unknown world of awakening dormant bacterial spores, researchers have revealed through atomic force microscopy (AFM) the alterations of spore coat and germ cell wall that accompany the transformation from a spore to a vegetative cell.

When starved of nutrients Bacillus (rod-shaped bacteria) cells initiate a series of genetic, biochemical and structural events that result in the formation of metabolically dormant spores. They can remain dormant for extended periods and, partly because of their tough spore coat, have a significant resistance to extreme environmental factors including heat, radiation and toxic chemicals. However, once in favorable conditions, spores break the dormant state through germination and reenter the vegetative mode of replication.

Although significant progress has been made in understanding the biochemical and genetic bases of the spore germination process, it is still unclear how a spore breaks out of its dormant state.

But a new in vitro study of single germinating Bacillus atrophaeus spores details how the spore coat structures break down, and it shows with unprecedented resolution how the new bacterium emerges from the disintegrating spore. The new research, led by Lawrence Livermore National Laboratory scientists, appears in the May 28-June 1 early online edition of the Proceedings of the National Academy of Sciences. The research appears in this week’s (June 4) issue of PNAS.

“A thorough understanding of spore germination is important for the development of new countermeasures that identify the earliest stages of a wide range of spore mediated diseases, including botulism, gas gangrene and pulmonary anthrax,” said Alexander Malkin, senior author from LLNL’s Biosciences and Biotechnology Division. “But it’s also important to gain fundamental insights into the key events in bacterial cell development.”

The researchers, including Marco Plomp, lead author at LLNL, and those from Children’s Hospital Oakland Research Institute and Northwestern University, used AFM to identify disassembly of the outer spore coat rodlet structures, which appear to be structurally similar to amyloid fibrils that have been associated with neural degenerative diseases, such as Alzheimer’s and prion diseases. “The extreme physical and chemical resistance of Bacillus spores suggests that evolutionary forces have captured the mechanical rigidity and resistance of these amyloid self-assembling biomaterials to structure the protective outer spore surface,” Plomp said.

When exposed to a solution that triggers germination, nanometer sized etch pits were seen developing in the rodlet layer. These etch pits evolved into ever widening fissures, leaving narrow strips of remaining rodlet structure. In the end, 1- to 3- nm-wide fibrils remained. The in vitro AFM imaging also revealed the porous fibrous cell wall structure of newly emerging and mature vegetative cells, consisting of a network of nanometer-wide peptidoglycan fibers. “These results show that dynamic AFM is a promising tool to investigate the formation and evolution of the bacterial cell wall,” Malkin said.

Source: Lawrence Livermore National Laboratory

Explore further: Bacteria use DNA replication to time key decision

Related Stories

Bacteria use DNA replication to time key decision

July 9, 2015

In spore-forming bacteria, chromosomal locations of genes can couple the DNA replication cycle to critical, once-in-a-lifetime decisions about whether to reproduce or form spores. The new finding by Rice University bioengineers ...

Bacteria cooperate to repair damaged siblings

May 21, 2015

A University of Wyoming faculty member led a research team that discovered a certain type of soil bacteria can use their social behavior of outer membrane exchange (OME) to repair damaged cells and improve the fitness of ...

Identifying the many layers of a bug's design

October 3, 2014

(Phys.org) —Lawrence Livermore researchers have discovered additional "coats," or layers, of a bacterium spore found in the human gut that may give clues to how this organism develops, spreads and survives in extreme conditions.

Salt needed: Tolerance lessons from a dead sea fungus

May 9, 2014

Despite its name, the Dead Sea does support life, and not just in the sense of helping visitors float in its waters. Algae, bacteria, and fungi make up the limited number of species that can tolerate the extremely salty environment ...

Recommended for you

Quantum matter stuck in unrest

July 31, 2015

Using ultracold atoms trapped in light crystals, scientists from the MPQ, LMU, and the Weizmann Institute observe a novel state of matter that never thermalizes.

Binary star system precisely timed with pulsar's gamma-rays

July 31, 2015

Pulsars are rapidly rotating compact remnants born in the explosions of massive stars. They can be observed through their lighthouse-like beams of radio waves and gamma-rays. Scientists at the Max Planck Institute for Gravitational ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.