Fig. 4.

Model 1: a Number of cells of each species in monoculture and coculture biofilms, grown in the absence and presence of sulfathiazole treatment: suppressed species 1 is able to grow after treatment. b Tolerance = ratio between the number of biofilm cells with and without sulfathiazole treatment, determined for each species in monoculture and coculture conditions. For each species the tolerance is equal or higher within the coculture biofilm. c Cooperation: both in the absence and presence of treatment the criterion for cooperation is not met. Growth of species 1 in coculture increases after treatment, but does not exceed its growth in monoculture. d Biodiversity effects in the absence and presence of treatment of the duo-species biofilm: dominating positive selection is replaced by positive complementarity after treatment. e Overview: inhibition of species 2 leads to a reduction in the competitive interactions against species 1, which allows species 1 to bloom. Results show the average of three biological replicates, except for a, which shows the average of three technical replicates of one representative biological replicate. Error bars show the standard deviation of the repeats. Significant differences were examined using unpaired t-tests with Bonferroni correction for multiple comparisons (**P < 0.01). Biodiversity effects that significantly differ from 0 were examined using a one-sample t-test (*P < 0.05)