Abstract
Considerable progress has been achieved for production of bioethanol from lignocellulosic biomass. However, increasing the substrate concentration has shown to decrease the ethanol productivity. In the present study, Saccharomyces cerevisiae and Pichia membreneferans were used for ethanol production from glucose and xylose sugars respectively in optimized conditions. Further, co-culture fermentations were conducted in three different strategies for 13 g of sugar (10 g of glucose and 3 g of xylose) and the best strategy was further used for ethanol production from ultrasonication assisted NaOH (UA-NaOH) pretreated and enzymatically saccharified in batch and fed-batch fermentation conditions. Further, fed-batch fermentation was used for separate hydrolysis and co-fermentation (SHCF) and simultaneous saccharification and co-fermentation (SSCF) in shake flask conditions. The highest ethanol production of 12.2 and 7.9 (g/L) was observed for fed-batch SSCF denannath grass (DG) and Hybrid napier grass (HNG) (Palkonal MBW as the enzyme) biomass (80 g) respectively in shake flask conditions. However, increasing the biomass concentration to 270 g produced an ethanol concentration of 77.6 and 51.3 (g/L) for DG and HNG respectively in fed-batch SSCF conditions in bioreactor. Nuclear magnetic resonance studies of the residual biomass of both DG and HNG revealed presence of lower carbohydrate content, demonstrating the efficiency of the fermentation strategy. Further Life cycle Analysis (LCA) was also conducted to analyzed the effect of the ethanol on different environmental conditionsThe substrate feeding strategy and the saccharifying enzymes play a major role for efficient bioethanol production with higher substrate loadings. Presence of lower carbohydrates and some lignin moieties demonstrating the efficiency of the SSCF strategy for maximum conversion of carbohydrates. Thus fed batch SSCF process can be considered as a promising technique for biorefinery based bioethanol production from Pennisetum sp. in the future.
Batch and Fed-Batch Fermentation System on Ethanol Production from Whey using Kluyveromyces marxianus
