At first glance, the amber and gold aura seen in front of you might look like the rings of a tree trunk. But these radioactive bands have been arranged by unexpected little creatures: bacteria.
Last week, researchers from the University of California San Diego, Stanford University and Pompeu Fabra University published a research paper in cell which suggests that bacterial communities, known as biofilms, are more complex than previously thought. The researchers found that biofilms can organize themselves in a dartboard pattern due to a mechanism the researchers believe is only found in plants and animals.
Even if you’ve never heard of biofilms before, you’ve definitely come across them. Some common ones are pond scum and even plaque, and even biofilms can keep shipwrecks at bay by coating the metallic exterior and preventing corrosion. According to the paper, the ring-like pattern highlighted in the new research is a consequence of the nitrogen pressure response pattern in the thin biofilm. Nitrogen is essential for cell growth, and while nitrogen is readily available to cells at the edge of the biofilm, it is limited near the center.
This nitrogen deficiency causes bacteria to starve and provokes a stress response. Higher metabolic stress in the interior of biofilms causes cells to release spores, or baby bacteria, used to survive harsh conditions. Each stage in this cycle of starvation, stress, and deformation is “frozen” in time and space to form the concentric rings of the different cell types of the biofilm.
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In the paper, the researchers suggest that forming the rings in this way follows a “clock and wave front process”. The ‘clock’, in this case the nitrogen stress response pattern, creates different phases of cell type regulation. “Wavefront” is the identification between one type of organization and the next. It is a similar mechanism that designs every part of the human backbone or plant roots.
“We see that biofilms are more complex than we thought,” Gürol Süel, a professor of molecular biology at the University of California San Diego, said in a press release. “It is clear that the ability of cells to divide themselves in space and time not only appeared with plants and vertebrates, but may be more than a billion years old.”
These findings could help researchers better understand clock mechanisms and wavefronts in plants and animals because bacteria are easier to operate in a research environment.
“Having a bacterial system allows us to provide some answers that are difficult to obtain in vertebrate and plant systems,” Sowell said in the statement. “Bacteria provide more experimentally accessible systems that can provide new development insights.”