Cycle analysis reveals potential storage of glucose when using a mineral medium and an intermediate lactate peak when using a complex medium
The product and substrate concentrations during a representative cycle in the SBR are shown in Figure 2 for both enrichments.  In the enrichment culture on mineral medium, glucose was converted to mainly acetate and butyrate with minor amounts of ethanol and lactate (Figure 2A). The formation of fermentation products proceeds after glucose depletion. The COD recovery during the cycle showed that during the glucose consumption phase the COD of consumed glucose is not fully recovered in the measured products (Figure S7A), while in the subsequent period in the cycle the product concentration increased and finally a full recovery of consumed COD is observed. This indicates formation of an intermediate product which is probably a storage product, most likely a polymer of glucose.