Exploring the aerobic stability, antioxidant and microbial community of Broussonetia papyrifera ensiled with ferulic acid esterase-producing Lactiplantibacillus plantarum in combination with cellulase and/or xylanase.

Background: Ferulic acid possesses certain antioxidant and antibacterial properties. Additionally, ferulic acid esterase (FAE) and cellulolytic enzymes have been associated with synergistic degradation of ferulic acid ester bonds, thereby facilitating greater release of ferulic acid from lignocellulose, which could have important effects on silage quality and aerobic stability.

Methods: This study examined the effects of ensiling Broussonetia papyrifera with FAE-producing Lactiplantibacillus plantarum (LP), cellulase (CE) and xylanase (XY) under aerobic exposure conditions. The following treatments were used: distilled water (CK), LP, LP + CE, LP + XY and LP + XY + CE. After 60 days of silage treatment, the samples were unsealed for aerobic exposure for 1, 3, 5, or 7 days.

Results: Compared with the CK treatment, the addition of FAE-producing L. plantarum significantly (P < 0.05) led to lower pH, reduced dry matter loss of the silage and increased lactic acid (LA) concentration after 60 d of ensiling (especially for the LP + CE and LP + CE + XY groups). During the aerobic exposure stage, the combined treatment with LP and enzymes effectively inhibited the increase in pH, significantly reduced the rate of dry matter loss and increased the LA concentration and aerobic stability of the silage (P < 0.05). Moreover, the LP + CE and LP + CE + XY treatment groups exhibited higher ferulic acid levels than the other groups did, corresponding with greater aerobic stability, especially for the LP + CE group, which remained stable. In this group, the pH values showed minimal change, increasing by only 0.31 (4.24-4.55) after 7 days of aerobic exposure. In addition, the LP and enzyme co-treatment was linked to shifts in the microbial community of the silage during aerobic exposure, with increased relative abundance of Lactiplantibacillus plantarum, and its abundance positively correlated with lactic acid and ferulic acid concentrations, while negatively correlated with ammonia nitrogen; and inhibited proliferation of spoilage-related bacteria (Enterobacter, Gluconobacter and Cladosporium).

Conclusions: The combination of FAE-producing L. plantarum and cellulase can be used as an effective method to increase the preservation efficiency and aerobic stability of B. papyrifera silage.