Biologists from the University of California San Diego and elsewhere have found that biofilm cells are organized in elaborate patterns, a feature previously only associated with higher-level organisms such as plants and animals.
“We are seeing that biofilms are much more sophisticated than we thought,” said Professor Gürol Süel, a researcher in the Division of Biological Sciences at the University of California San Diego, the San Diego Center for Systems Biology, the BioCircuits Institute, and Center for Microbiome Innovation.
“From a biological perspective our results suggest that the concept of cell patterning during development is far more ancient than previously thought.”
“Apparently, the ability of cells to segment themselves in space and time did not just emerge with plants and vertebrates, but may go back over a billion years.”
Biofilms, which are prevalent in the living world, inhabiting sewer pipes, kitchen counters and even the surface of our teeth, are made up of cells of different types.
Biologists previously had not thought that these disparate cells could be organized into regulated complex patterns.
For the new study, Professor Süel and colleagues developed experiments and a mathematical model that revealed the genetic basis for a ‘clock and wavefront’ mechanism, previously only seen in highly evolved organisms ranging from plants to fruit flies to humans.
As the biofilm expands and consumes nutrients, a ‘wave’ of nutrient depletion moves across cells within the bacterial community and freezes a molecular clock inside each cell at a specific time and position, creating an intricate composite pattern of repeating segments of distinct cell types.
The breakthrough for the authors was the ability to identify the genetic circuit underlying the biofilm’s ability to generate the biofilm community-wide concentric rings of gene expression patterns.
They were then able to model predictions showing that biofilms could inherently generate many segments.
“Our discovery demonstrates that bacterial biofilms employ a developmental patterning mechanism hitherto believed to be exclusive to vertebrates and plant systems,” they said.
The results appear in the journal Cell.
Kwang-Tao Chou et al. 2022. A segmentation clock patterns cellular differentiation in a bacterial biofilm. Cell 185 (1): 145-157.e13; doi: 10.1016/j.cell.2021.12.001
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