bioreactor studies of heterologous protein production by ...

3.3. Analytical Methods
3.3.1. Cd CoIl~eIltiati0~
Free ceil concentration was measured by dry weight and optical density methods. The dry
weight ceil concentration was detennined by fiiteriag 20 ml of a sample through 0.2-pm
nIter papei, which was washed with deionized water Mce and then dried at 100 O C for 24
hours. The optical density (OD) was measured at 600 nm using a Turner (Mode1 330)
spectrophotometer. The comlation between dry celi weight ce11 concentration (X) and
opticai density (OD) was then determined as X = IR038 OD + 01726 . Immobilized ce11
mass was determined h m total weight of the dricd Cotton materiai containing ce& less
the weight of the corton matenal alone.
3.3.2. Glucose Measurement
Glucose concentrations were determined using glucose kit (Procedm No. 510) hm
Sigma (SC. Louis. Mo). The Sigma procedure is based upon the foilowing coupled
enzymatic reactions:
Glucose + 2H20 + O, Glucose Oxiciirse Gluconk Acid + 2 40,
H,O, + O - DknrSidine [Colorkss] Peroxùiàse , Oxidized o - Dianisidine [Brown]
nie intensity of the brown color measured at 425475 nm is proportional to the original
glucose concentration. The measurement procedure is outlined as foilows according to
the manuai: