Study on various degradation mechanisms of lignocellulose during spontaneous ensiling and their contributions to 2G bioethanol production

The degradation of lignocellulose during spontaneous ensiling is known to exist, probably from the action of microorganisms, enzymes and acids. Therefore, it is necessary to clarify the three lignocellulosic degradation mechanisms in the above processes, which can guide silage pretreatment strategy and downstream biofuel production. The study aimed to investigate the effects of microorganism-, enzyme-, or acid-based degradation on lignocellulosic degradation during ensiling and subsequent bioethanol production. Forage oat (FO) was treated as follows: sterile water + FO (CON); FO epiphytic microbiota + irradiated and enzyme-inactivated FO (MD), sterile water + irradiated FO (ED), and organic acid mixture + irradiated and enzyme-inactivated FO (AD). Among MD, ED and AD treatments, MD had the highest lignocellulose degradation rate (LDR) of 25.3 % and ethanol yield of 47.1 % due to the synergistic effect of microorganisms and organic acids. While in AD treatment, without microbial activity, the LDR and ethanol yield decreased to 9.18 % and 40.3 %, respectively. The lowest LDR (6.24 %) and ethanol yield (30.3 %) were observed in ED treatment. These results manifested that the future ensilage regulation strategies for biorefinery should focus more on microorganisms to maximize 2 G bioethanol production.