Measuring Enterobacter sp. LU1 Growth

Cell growth was monitored by measuring the absorbance of the broth at 600 nm (OD600) after diluting the sample 1:1 with 7% HCl (v/v). The biomass concentration of the Enterobacter sp. LU1 strain was estimated by determining the dry cell weight (DCW) using a predetermined correlation curve obtained between the absorbance measured at 600 nm and the cell dry weight (g/l). One unit of OD600 was roughly equivalent to 0.51 g/l of DCW for cells of Enterobacter sp. LU1 grown in BHI medium (Podleśny et al. 2017 (link)). Samples for succinic acid and by-product detection were prepared by centrifugation of the culture broth at 6000×g for 5 min. The resulting supernatant, after dilution with water (1:1), was analyzed by high-performance liquid chromatography system (Gilson) equipped with an ion exchange column (Aminex HPX-87H, BioRad) and a refractive index detector using 0.03 M sulfuric acid as mobile phase at 42 °C (Dharmadi et al. 2006 (link)).