The study firstly established oxidative stress injury model of human embryonic kidney cells (HEK293) by the induction of 2, 2-azobis (2-methylpropionamidine) dihydrochloride (AAPH) to evaluate the antioxidant activity of five wheat protein-derived peptides Leu-Tyr (LY), Pro-Tyr (PY), Tyr-Gln (YQ), Ala-Pro-Ser-Tyr (APSY) and Arg-Gly-Gly-Tyr (RGGY). Then, it used quantum chemistry and molecular docking techniques to predict the optimal configuration and binding effect of five wheat protein-derived peptides combined with 2, 2-azinobis- (3-ethylbenzthiazoline-6-sulphonate) (ABTS), and to explore the molecular mechanism of wheat protein-derived peptides. The results of cell test show that after the action of five wheat protein-derived peptides, the cell death rate significantly decreases to below 3.68% (P ＜ 0.05), and the generation of reactive oxygen species (ROS) induced by AAPH was significantly reduced (P ＜ 0.05), making the ROS content tend to normal levels. All five wheat proteinderived peptides show good total antioxidant capacity and free radical scavenging capacity of 1, 1-Diphenyl-2-picrylhydrazyl (DPPH) (P ＜ 0.05). RGGY shows the strongest total antioxidant capacity, with an activity value of (1.46 ± 0.08) mmol/L Trolox, followed by APSY, YQ, PY and LY. The DPPH free radical scavenging ability of YQ is the strongest, with a scavenging rate of 61.34% ± 2.24%, followed by APSY, RGGY, PY and LY. The results of molecular docking show that the CDOCKER interaction energy (-CIE) scores of the five wheat protein-derived peptides are 13.3049, 13.3973, 13.4121, 16.7685 and 16.2683, respectively, which can effectively interact with ABTS, mainly through the formation of strong hydrogen bonds and hydrophobic forces between ABTS molecules to exert antioxidant activity.

The cost of dairy manure treatment and bedding material purchase increases the operating cost of the dairy farm. Membrane-covered aerobic fermentation system has been widely used for dealing with dairy manure and recycling the final product as bedding material. However, the microbial safety in each processing step is still uncertain. To better understand the bacterial community dynamics during the whole bedding conversion process, a full-chain and large-scale experiment including 16-day membrane-covered aerobic fermentation and 11-day bedding material application was conducted. The results showed that the pile temperatures in the fermentation stage rapidly increased to 80°C and maintained >50°C for more than 11 d and the use of fermentation product as bedding material provided cows with a stable and comfortable bedding environment. The Chao1 and Shannon index decreased at the end of the fermentation stage and remained stable in the application stage, indicating that membrane-covered aerobic fermentation effectively killed some pathogenic bacteria and guaranteed both the maturity and stability of the final product. The dominant bacteria in the fermentation stage were Acinetobacter, Thermus, and Rhodothermus at genus level. Seven common potential pathogens of mastitis (Staphylococcus, Enterococcus, Serratia, Pseudomonas, Corynebacterium, Mycobacterium, and Bacillus) were found at the end of fermentation stage but the relative abundance was low (0.0025%-0.2727%). The dominant bacteria in the application stage mainly included Acinetobacter, Pseudomonas, and Flavobacterium at the genus level. The relative abundance of Pseudomonas increased in the application stage, which was a reminder to the dairy farm to pay attention to the disinfection and timely replacement of bedding material to prevent the occurrence of dairy mastitis. The results of this study contributed deep understanding of the microorganism-driven bedding conversion process and provide practical guidance and cautions for the bedding materials application.