Improvement of bioethanol production using a new fermentation system: The process analysis and micro-mechanisms study

Rice straw based bioethanol is a clean alternative energy source to alleviate the energy crisis and greenhouse gases emission. However, the efficient alkali pretreatment of rice straw for bioethanol production will generate several fermentation inhibitors, such as ferulic acid, which could inhibit bioethanol fermentation. Therefore, an adsorbent called Air Environment-Prepared Adsorbent at 250 ℃ (AEPA₂₅₀) was prepared using the enzymatically hydrolyzed residue of rice straw to detoxify ferulic acid in this study for enhancing the subsequent bioethanol production. Analysis of the mass balance showed that ferulic acid detoxification by AEPA₂₅₀ had a high removal efficiency of 94.393% with a low glucose and xylose loss of 2.532% and 8.219%, respectively. A higher 277.551 mg/L bioethanol concentration and 76.005% glucose consumption rate in the SSBP system were obtained compared to non-detoxified sample. Furthermore, proteomics analysis indicated that certain metabolic pathways of TCA cycle and ribosome pathway as well as various coded proteins of ACO1, MRP2, RPL24B, MRPL33, RPL32, RPL39, RPS17B, RPS19A, RPS26A and ATP5 contributed to ferulic acid detoxification in the SSBP system. The findings of this study may help develop efficient pretreatment methods, detoxification strategies and engineering yeast strains for improving bioethanol production in the future.