Figure 1.

Time course of succinic acid (SA) production by batch fermentation using Enterobacter sp. LU1. (A) With glycerol (99.6%) and lactose. (B) With crude glycerol (85.0%) and whey permeate (77.0% of lactose). GLY (glycerol) (◊), LAC (lactose) (Δ), FA (formic acid) (x), AA (acetic acid) (□), EtOH (ethanol) (●), Biomass (■). The fermentation was carried out at 34 °C in a 2 L bioreactor with pH control by (A) automatic addition of 5% NaOH (w/v) and 20% Na₂CO₃ (w/v) or (B) manual addition of sterile MgCO₃ to avoid pH decrease below 7.0. For the first 6 h, stirring was performed at 500 rpm with airflow at 1.0 vvm and was then decreased to 250 rpm without aeration. The values are the means of two independent samples.