2.4.3 Analytical methods
Biomass formation has been measured at specific time points by assessing the optical density (OD600 nm) using a spectrophotometer (Cary50Conc, UV–vis Spectrophotometer, Australia). For the determination of ethanol and glucose concentrations, the main culture was harvested by centrifugation (6000×g, 12 min, 4°C), and the supernatant was analyzed via G.C. The Glucose concentrations were measured enzymatically using a colorimetric glucose oxidase kit (Pars Azmun, Iran).
The concentration of ethanol was determined by using gas chromatography GC-2550TG (Teif Gostar Faraz Company, Iran), Hydrogen gas as the carrier gas and the injection, column and flame ionization detection (FID) temperature was maintained at 120°C, 250°C and 250°C respectively. Ethanol (99/9%, Merck) was used as the internal standard.