Trehalose improves cold tolerance of Pediococcus pentosaceus OL77 and enhances low-temperature oat silage fermentation

ABSTRACT Low temperature remains a major bottleneck in silage fermentation, especially in cold regions and high-altitude areas. This study investigated the regulatory role of compatible solutes in enhancing the cold adaptation of Pediococcus pentosaceus OL77 and their synergistic application in oat silage under suboptimal temperatures (5°C–15°C). RT-qPCR analysis showed that expression of the cold shock protein gene CspP was sharply induced at 5°C, indicating its central role in cold-stress response. Exogenous trehalose and betaine significantly downregulated CspP expression, promoted bacterial growth, accelerated acid production, and enhanced metabolic stability. In silage trials, the OL77 + trehalose treatment resulted in improved lactic acid production, reduced ammonia nitrogen accumulation, and suppression of yeasts and molds across all tested temperatures. A random forest model identified 11 core variables critical for silage quality, highlighting the combined treatment as the most effective across all temperature conditions. These findings offer a robust theoretical and practical framework for enhancing low-temperature silage through synergistic application of compatible solutes and psychrophilic lactic acid bacteria and demonstrate the potential of machine learning in fermentation process optimization. IMPORTANCE Low temperature is a major constraint on silage fermentation in cold and high-altitude regions. This study shows that trehalose improves the cold adaptation and fermentation performance of Pediococcus pentosaceus OL77, highlighting a practical strategy for improving oat silage quality under suboptimal temperatures.