Purple bacteria contain pigments that allow them to use sunlight as their source of energy, hence their color. Small as they are, these microbes can teach us a lot about life on Earth, because they have been around longer than most other organisms on the planet.
Purple bacteria make a "gel" around the individual cells which binds them into a colony. That is why they appear as "clouds." The insert illustrates the general principle of the model used in the study. It depicts photons arriving, then being passed around the bacteria's membrane, where the light harvesting mechanism is located, then arriving at the various reaction center 'kitchens', being processed, and then being turned out as metabolic products for the bacteria to survive.
Credit: Dr. Wayne B. Lanier
University of Miami (UM) physicist Neil Johnson, who studies purple bacteria, recently found that these organisms can also survive in the presence of extreme alien light. The findings show that the way in which light is received by the bacteria can dictate the difference between life and death.
Johnson, head of the inter-disciplinary research group in complexity in the College of Arts and Sciences at UM and his collaborators share their findings in a paper titled "Extreme alien light allows survival of terrestrial bacteria" published online in Nature's Scientific Reports. The study reveals new possibilities for life on earth and elsewhere in the universe.
"The novelty of our work is that despite all the effort aimed at finding planets outside our solar system where life might exist, people have ignored the fact that photosynthesis--and hence life on Earth-- isn't just about having the right atmosphere and light intensity," Johnson says. "Instead, as we show, a crucial missing ingredient is how the light arrives at the organism."
The results are also applicable in the scenario of our own sun developing extreme fluctuations and in a situation in which bacteria are subject to extreme artificial light sources in the laboratory.
The findings may also help with engineering a new generation of designer-light-harvesting structures.
Using a mathematical model the researchers calculated the probability of survival when the bacteria is subjected to bursts of light, similar to what might be experienced if the light source was an unstable star. The flow of light was on average the same as the bacteria would normally receive, but since they would be receiving it in such a strange way, the researchers wondered under what situations the bacteria could survive.
"It's like saying we know we need to bring home a certain amount of food per week, but what happens if all of the food is delivered in one day? You might not be able to store all of it," Johnson says. "Maybe some food would get spoiled, or maybe you wouldn't have time to use it all," he says. "The light is like food for the bacteria, and the issue is the amount of food and the timing with which you bring it in."
Light comes in packets of photons. Purple bacteria process light in places callereaction centers, where the energy of the photons fuels the production of metabolic materials. Johnson compares the situation to asking what happens when food arrives in the kitchen in an irregular way.
"The reaction center, like any kitchen, can't do a thousand things at once. They can only handle one photon at a time," Johnson says. "The new chemicals made in the process take some time to diffuse. Otherwise, it results in a buildup of chemicals that can kill the bacteria," he says. "Since we are concluding this from statistical calculations, we can say it's very unlikely that the bacteria will survive."
To their surprise, the researchers found that while many seemingly innocuous changes in the way the light arrives at the organisms end up proving fatal, the bacteria could survive a sudden deluge of photons. The key to enduring such extreme conditions is that that there are many reaction center 'kitchens.' Therefore, the photons spread out naturally, leaving each reaction center enough time to recover.
"Ultimately the chemicals have time to diffuse and that is what saves it," Johnson says. "On the average the bacteria is therefore getting what it needs from the reaction centers."
The researchers suspect this mechanism is not unique to purple bacteria. In the future, they will expand the study to other photosynthetic life forms.
Co-authors of the study are Guannan Zhao, who was a postdoctoral fellow at UM at the time of the project; Pedro Manrique and Hong Qi doctoral students at UM; Felipe Caycedo, postdoctoral fellow at Universitat Ulm, Germany; Ferney Rodriguez and Luis Quiroga, professors at Universidad de Los Andes, Bogota, Colombia.
The University of Miami's mission is to educate and nurture students, to create knowledge, and to provide service to our community and beyond. Committed to excellence and proud of our diversity of our University family, we strive to develop future leaders of our nation and the world. http://www.miami.edu.
Annette Gallagher | EurekAlert!
Progress in Super-Resolution Microscopy
17.12.2018 | Julius-Maximilians-Universität Würzburg
Communication between neural networks
17.12.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau
Researchers from the University of Basel have reported a new method that allows the physical state of just a few atoms or molecules within a network to be controlled. It is based on the spontaneous self-organization of molecules into extensive networks with pores about one nanometer in size. In the journal ‘small’, the physicists reported on their investigations, which could be of particular importance for the development of new storage devices.
Around the world, researchers are attempting to shrink data storage devices to achieve as large a storage capacity in as small a space as possible. In almost...
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
17.12.2018 | Studies and Analyses
17.12.2018 | Life Sciences
17.12.2018 | Power and Electrical Engineering