2.6. Data analysis
As the fermentation went on, SLs was gradually accumulated in the broth and once the O/S ratio reached at a certain range, the SLs sedimentation was occurred. The average sedimentation rate was calculated by formula (1). By fitting the height of SLs sedimentation was directly proportional to the concentration of SLs, formula (2) was obtained. The sedimentation rate formula related to SLs concentration could be derived in (3).
\(\overset{\overline{}}{V}=\frac{H_{1}-H_{2}}{2t}\) (1)
\(\frac{H_{2}}{H_{1}}=0.0031\times c-0.0001\) (2)
\(\overset{\overline{}}{V}=\frac{H_{1}-H_{1}(0.0031\times c-0.0001)}{2t}\)(3)
Where \(\overset{\overline{}}{V}\) is the average sedimentation rate of SLs in cm/s, H1 is the height of broth in the 10 mL sedimentation tube in cm, H2 is the height of SLs settled in the 10 mL sedimentation tube in cm, t is settling time in s, c is SLs concentration in g/L.
Due to the consideration of working volume change by feeding, all the presented data in Figures and Tables were normalized to the initial volume. All experiments were performed in triplicate.