Microbial Community Cultivation and Characterization

We used the cells of a microbial community originating from an activated sludge basin of a wastewater treatment plant (Eilenburg, Saxonia, Germany—51°27’39.4″ N, 12°36’17.5″ E) as our model microbial community described in Liu et al. [21 (link)]. The entire workflow employed in this study, including the experimental scheme of the sequential batch cultivation and treatment of the microbial community, is presented in Supplementary File S1: Figure S1A,B. The activated sludge sample (30 mL thawed inoculum) was first cultured in a 1-L batch flask in 300 mL medium at 30 °C and 125 rpm for 17 h to reduce the undegraded and inorganic particles from the sludge. The second and third batches (each also in 1-L flasks) were inoculated with an initial optical density (OD) of 0.05 (OD_600nm, d = 0.5 cm), each, and cultivated in the same way.
The medium was a mixture of 98% synthetic wastewater and 2% peptone. The medium constituted 0.198 g L⁻¹ peptone (from meat), 0.2 g L⁻¹ meat extract, 0.219 g L⁻¹ yeast extract, 0.1 g L⁻¹ glucose, 0.49 g L⁻¹ Na-propionate (filtered), 0.0059 g L⁻¹ CaCl₂·2H₂O, 0.0294 g L⁻¹ KCl, 0.06 g L⁻¹ NaCl, 0.04 g L⁻¹ K₂HPO₄, 0.2156 g L⁻¹ KH₂PO₄ and 0.0196 g L⁻¹ MgSO₄·7H₂O, purchased from: Merck KGaA (Darmstadt, Germany), SERVA Electrophoresis GmbH (Heidelberg, Germany) and Carl Roth GmbH (Karlsruhe, Germany).