Optimization of diluted alkali and hot water pretreatments in bioethanol production from switchgrass (Panicum virgatum L.) and determination of ethanol yields of some genotypes

In this study, optimization of bioethanol production was performed by alkali and hot water pretreatments from switchgrass (Panicum virgatum L.) which is known as an energy crop type. Firstly, biomass was hydrolyzed with 3 different enzyme dosages for 7 days so that optimum dosage and time was determined. After the determination of optimum enzyme dosage and incubating time, switchgrass pyrolyzed in high pressure reactor with NaOH (in two different concentrations 0.5% and 1.0% (w/v)) and hot water under the several heat treatments (120,140 and 180°C) for three different process time (10, 60, 90 min). In order to determinate optimum fermentation conditions, fermentation was carried out by Saccharomyces cerevisiae and4 different conditions (2 temperature and 2 media) was constituted. Optimum pyrolysis and fermentation conditions were determined by using data which were received from HPLC and bioethanol was produced from 10 different genotypes. According to obtained results, maximum total fermentable sugar amount was found as 42.94 g/100 g switchgrass, optimum pyrolysis condition was 120°C, 1.0% of NaOH treatment for 10 minutes. Furthermore, maximum ethanol yield was emerged at 25°C and 4 g L-1 yeast extract added media and yield was found as 0.0966 g ethanol/100 g switchgrass. Results showed that the bioethanol yields from 10 genotypes were ranging between 7.44 and 9.94 g/100 g switchgrass.