Mechanistic insights into fungal succession mediated by Pichia kudriavzevii during aerobic deterioration of ensiled total mixed ration.

backgroundAerobic deterioration of ensiled total mixed ration (ETMR) represents a critical challenge in livestock feed preservation, yet the microbial drivers of this process remain poorly characterized. Although Pichia kudriavzevii has been identified as the predominant spoilage yeast in ETMR, its ecological role in fungal community assembly and succession during aerobic deterioration remains unclear. This study elucidates the impact of P. kudriavzevii on aerobic stability and fungal succession in alfalfa and oat based ETMR, inoculated with or without P. kudriavzevii and analyzed after 42 days ensiling.

resultsChemical analyses and high-throughput sequencing demonstrated that P. kudriavzevii inoculation significantly reduced aerobic stability (P<0.05) without affecting fermentation quality. P. kudriavzevii substantially altered fungal communities during both ensiling and aerobic exposure, displaying increased relative abundancewhile suppressing Saccharomyces cerevisiae and Monascus purpureus. Although interspecific fungal interactions were generally weak, a strong negative correlation was identified between P. kudriavzevii abundance and lactic acid concentration (R=-0.789, P<0.001), coinciding with progressive pH elevation during aerobic exposure.

conclusionThe findings establish that P. kudriavzevii drives aerobic deterioration mainly through lactic acid catabolism, with its effects depending on intraspecific diversity. This study provides fundamental insights into fungal-driven spoilage mechanisms in ETMR, highlighting potential microbiome-based targets for enhancing silage preservation. Specifically, the results suggest that controlling P. kudriavzevii proliferation or its metabolic activity could represent an effective strategy for preventing aerobic spoilage in ensiled feeds.