According to the study, purple bacteria adapt to different light intensities by changing the arrangement of the light harvesting mechanism, but not in the way one would think by intuition.
"One might assume that the more light the cell receives, the more open reaction centers it has," says Johnson. "However, that is not always the case, because with each new generation, purple bacteria create a design that balances the need to maximize the number of photons trapped and converted to chemical energy, and the need to protect the cell from an oversupply of energy that could damage it."
To explain this phenomenon, Johnson uses an analogy comparing it to what happens in a typical supermarket, where the shoppers represent the photons, and the cashiers represent the reaction centers.
"Imagine a really busy day at the supermarket, if the reaction center is busy it's like the cashier is busy, somebody is doing the bagging," Johnson says. "The shopper wonders around to find an open checkout and some of the shoppers may get fed up and leaveThe bacteria are like a very responsible supermarket," he says. "They would rather lose some shoppers than have congestion on the way out, but it is still getting enough profit for it to survive."
The study develops the first analytical model that explains this observation and predicts the "critical light intensity," below which the cell enhances the creation of RCs. That is the point of highest efficiency for the cell, because it contains the greatest number and best location of opened RCs, and the least amount of energy loss.
Because these bacteria grow and repair themselves, the researchers hope this discovery can contribute to the work of scientists attempting to coat electronic devices with especially adapted photosynthetic bacteria, whose energy output could become part of the c
|Contact: Marie Guma-Diaz|
University of Miami