Insight into the lignocellulosic degradation patterns during spontaneous ensiling and their contributions to bioethanol production

The degradation of lignocellulose during spontaneous ensiling is known to exist, mainly due to the action of microorganisms, enzymes and acids. Therefore, it is necessary to investigate the relative contribution of the three factors to lignocellulosic degradation, which can guide silage modulation strategy and even downstream biofuel production. The aim of this study was to investigate the effects of microorganism-, enzyme-, or acid-based degradation on lignocellulosic degradation during ensiling and subsequent bioethanol production. Annual ryegrass was treated as follows: sterile water + IR (CON); IR epiphytic microbiota + irradiated and enzyme-inactivated IR (MD), sterile water + irradiated IR (ED), and organic acid mixture + irradiated and enzyme-inactivated IR (AD). Among MD, ED and AD treatments, MD had the highest lignocellulose degradation rate (LDR) of 24.3 % and ethanol yield of 53.2 % due to the synergistic effect of microorganisms and organic acids. While in AD treatment, without microbial activity, the LDR and ethanol yield decreased to 11.2 % and 46.6 %, respectively. The lowest LDR (7.23 %) and ethanol yield (34.8 %) were observed in ED treatment. These results manifested that microorganism-based degradation played a leading role in the lignocellulose degradation during ensiling and contributed more to the increase of bioethanol production. Therefore, Future ensilage regulation strategies should focus more on microorganisms to maximize bioethanol conversion efficiency.