Like human societies--think New York City--bacterial colonies have immense diversity among their inhabitants, often generated in the absence of specific selection pressures, according to a paper published ahead of print in the Journal of Bacteriology.
Microbiologists have long been aware of this phenomenon, and they credit it as a reason microbes have been able to colonize almost every conceivable terrestrial habitat from underground Antarctic lakes to hot springs to intensely radioactive pools, says corresponding author Ivan Matic, of INSERM, Paris. But none had tried to track it at the level of single cells.
"By using up to date experimental tools that allowed us to follow individual living cells, we were able to enter into this amazing, beautiful world of bacterial multicellular structures," says Matic.
"We observed massive phenotypic diversification in aging Escherichia coli colonies. Some variants showed improved capacity to produce biofilms, whereas others were able to use different nutrients, or to tolerate antibiotics, or oxidative stress, compared to the ancestral strain."
In the study, the researchers started each colony with a small number of identical cells, and observed them as they grew and as the colony aged. An aging colony is one where growth has stopped, because nutrients have been exhausted and/or toxins have accumulated.
"At this point most cells in the colony stop dividing and dead cells accumulate," says Matic.
Even in the growth phase, a colony is environmentally diverse. For example, since it grows on a solid medium, nutrients diffuse from the bottom up, resulting in a nutritional gradient with lower levels at greater elevation above the medium.
Similarly, oxygen and UV radiation decline with distance from the colony's surface, so that cells close to the top have ample oxygen, while those well below exist under anaerobic conditions.
In the elderly colony, the rising toxins and falling nutrients are also not homogeneously distributed. For example, despite general nutrient depletion, new nutrients become available from dead cells.
"We showed that the rare survivors of a senescent colony are very diverse and are different from their ancestors," says Matic. "We found different metabolic capacities, different levels of stress resistance, improved capacity to produce biofilms, and the ability to use different nutrients.
Some of these capacities probably evolved due to obvious selection pressures, such as utilization of alternative energy sources."
Journal of Bacteriology is a publication of the American Society for Microbiology (ASM). The ASM is the largest single life science society, composed of over 39,000 scientists and health professionals. Its mission is to advance the microbiological sciences as a vehicle for understanding life processes and to apply and communicate this knowledge for the improvement of health and environmental and economic well-being worldwide.
Jim Sliwa | Eurek Alert!
Discovery of a fundamental limit to the evolution of the genetic code
03.05.2016 | Institute for Research in Biomedicine (IRB Barcelona)
03.05.2016 | Christian-Albrechts-Universität zu Kiel
Using an ultra fast-scanning atomic force microscope, a team of researchers from the University of Basel has filmed “living” nuclear pore complexes at work for the first time. Nuclear pores are molecular machines that control the traffic entering or exiting the cell nucleus. In their article published in Nature Nanotechnology, the researchers explain how the passage of unwanted molecules is prevented by rapidly moving molecular “tentacles” inside the pore.
Using high-speed AFM, Roderick Lim, Argovia Professor at the Biozentrum and the Swiss Nanoscience Institute of the University of Basel, has not only directly...
If a person pushes a broken-down car alone, there is a certain effect. If another person helps, the result is the sum of their efforts. If two micro-particles are pushing another microparticle, however, the resulting effect may not necessarily be the sum their efforts. A recent study published in Nature Communications, measured this odd effect that scientists call “many body.”
In the microscopic world, where the modern miniaturized machines at the new frontiers of technology operate, as long as we are in the presence of two...
Researchers from the Max Planck Institute Stuttgart have developed self-propelled tiny ‘microbots’ that can remove lead or organic pollution from contaminated water.
Working with colleagues in Barcelona and Singapore, Samuel Sánchez’s group used graphene oxide to make their microscale motors, which are able to adsorb lead...
Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.
In a paper published in Physical Review Letters, researchers at the Department of Energy's Oak Ridge National Laboratory describe a new tunneling state of...
Honeycomb structures as the basic building block for industrial applications presented using holo pyramid
Researchers of the Alfred Wegener Institute (AWI) will introduce their latest developments in the field of bionic lightweight design at Hannover Messe from 25...
27.04.2016 | Event News
15.04.2016 | Event News
12.04.2016 | Event News
03.05.2016 | Physics and Astronomy
03.05.2016 | Life Sciences
03.05.2016 | Physics and Astronomy