Ensiling with rumen fluid promoted Irpex lacteus colonization on the non-sterile naked oat straw for enhanced lignocellulose degradation and enzymatic hydrolysis

Abstract

White rot fungi (Irpex lacteus) pretreatment is a promising method to improve lignocellulose utilization, and most current investigations have been conducted under sterile conditions. The objective of this study was to develop a novel naked oat straw pretreatment strategy, which replacing autoclave-based sterilization prior to I. lacteus inoculation by ensiling with 0%, 1%, 3%, and 5% rumen fluid (w/w) on a fresh matter basis. The results showed that ensiling with rumen fluid improved fermentation quality obviously. The dominant bacterial genera were Streptococcus and Pediococcus compared to Pantoea in control, which corresponded to a higher lactic acid content and lower pH. After 28 days of I. lacteus inoculation, species relative abundance was significantly higher in rumen fluid ensiling groups. Moreover, there was a highly negative correlation between the presence of I. lacteus and acid detergent lignin content. Enzymatic hydrolysis analysis also determined that rumen fluid ensiling groups promoted favorable conditions for reducing sugar content and hydrolysis yield, with the highest values observed in the 3% rumen fluid addition group. The investigation indicates that ensiling with rumen fluid create a highly favorable environment for I. lacteus proliferation under non-sterile conditions; which enhanced lignocellulose degradation and enzymatic hydrolysis correspondingly.