NMDS analysis plot. T-RFLP profiles of bacterial 16 S rRNA amplicons digested with the restriction enzyme Msp I (column A). Sampling times are indicated by red squares. Community similarity is based on the Bray-Curtis index which includes the presence and relative abundance of T-RFs. Blue arrows indicate the correlation vectors of community differences and the process parameters with significance factors p < 0.05. Black arrows indicate the correlation vectors of single T-RFs and the process parameters with significance factors p < 0.01. Significance was tested by Monte-Carlo permutation against 999 random data sets. Green hulls indicate the three metabolic phases of the batch experiment (see Figure 3).