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Abstract

Bacterial cells in nature are frequently exposed to changes in their
chemical environment(1,2). The response mechanisms of isolated cells to
such stimuli have been investigated in great detail. By contrast, little
is known about the emergent multicellular responses to environmental
changes, such as antibiotic exposure(3-7), which may hold the key to
understanding the structure and functions of the most common type of
bacterial communities: biofilms. Here, by monitoring all individual
cells in Vibrio cholerae biofilms during exposure to antibiotics that
are commonly administered for cholera infections, we found that
translational inhibitors cause strong effects on cell size and shape, as
well as biofilm architectural properties. We identified that
single-cell-level responses result from the metabolic consequences of
inhibition of protein synthesis and that the community-level responses
result from an interplay of matrix composition, matrix dissociation and
mechanical interactions between cells. We further observed that the
antibiotic-induced changes in biofilm architecture have substantial
effects on biofilm population dynamics and community assembly by
enabling invasion of biofilms by bacteriophages and intruder cells of
different species. These mechanistic causes and ecological consequences
of biofilm exposure to antibiotics are an important step towards
understanding collective bacterial responses to environmental changes,
with implications for the effects of antimicrobial therapy on the
ecological succession of biofilm communities.