Fig. 6

Relative effect of a salt concentration and b time on the 32 and 20 phylotypes (●) that showed a significant different abundance in function of salt concentration and time, respectively (out of a total of 79 phylotypes). These phylotypes had minimum relative abundance >0.1% in at least one sample, and were present in all samples. Average values of the parameter estimation of the multivariate abundance model of all samples (excluding the feed sludge samples) are presented, and ordered from the most negative (negative effect) to the most positive (positive effect) values. The effect strength of time was additionally dependent on the RNA/DNA ratio for 21 phylotypes (■), while this could only be observed for two phylotypes for the salt effect (not included in the figure). Error bars represent standard errors of the parameter estimation of the model. A smoothing function was fitted to the data for illustration of trends (local regression)