Enhancing low-temperature fermentation quality and modulating bacterial community of whole-plant maize silage using a novel cold-tolerant Lacticaseibacillus paracasei.

Maize (Zea mays L.) is a vital global crop for food, feed, industry, and energy production, with fermentation being critical in its processing. In the Qinghai-Tibet Plateau, the industrial-scale production of whole-plant maize silage faces substantial challenges of low lactic acid bacteria activity and fermentation efficiency. This study assessed the effects of inoculating whole-plant maize silage with a novel cold-tolerant lactic acid bacteria, Lacticaseibacillus paracasei YZ3, compared to a control (CON, without inoculant) and a commercial LAB strain (LPC, Lactiplantibacillus plantarum), on the fermentation characteristics, chemical composition, and microbial community during ensiling at 15 °C and 25 °C for 30, 60, and 90 days. Results indicated that YZ3 inoculation improved fermentation quality in low temperature conditions, evidenced by higher (P < 0.05) lactic acid content and lower pH, and propionic acid content at 15 °C. Conversely, LPC inoculation demonstrates superior lactic acid production at 25 °C. High-throughput sequencing revealed that YZ3-treated silage promoted the proliferation of Lactiplantibacillus (especially L. plantarum) and contributed to maintaining the stability of its relative abundance at days 90 under low-temperature. Meanwhile, YZ3 inoculation also enhanced amino acid metabolism at days 30 and 60, and sustaining high efficiency carbohydrate metabolism in late-stage. These findings demonstrated that L. paracasei YZ3, as an effective inoculant, could improve fermentation quality of whole-plant maize silage under low-temperature, holding significant importance for optimizing the preservation of important crops like whole-plant maize in challenging low-temperature environments.