Co-culture fermentation of Debaryomyces hansenii and Bacillus atrophaeus alleviates quality deterioration of litchi fruit by ameliorating microbial community diversity and composition.

Microbial communities, both on the surface and within fruit, play a crucial role in reducing postharvest diseases and maintaining fruit quality. This study investigated the effects of co-culture fermentation supernatant of Debaryomyces hansenii (Y) and Bacillus atrophaeus (T) on disease control and quality preservation of postharvest litchi fruit, while exploring the underlying mechanisms through microbiome profiling. The results indicated that Y + T treatment not only reduced decay percentage, weight loss, and pH increase but also preserved the pericarp cell integrity and reduced the lignin accumulation. Additionally, it delayed changes in firmness, chroma value, anthocyanin content, and the contents of soluble sugar, protein, and vitamin C during storage. High-throughput sequencing revealed significant differences in the diversity and richness of bacterial and fungal species between the control and Y + T-treated fruit. The Y + T treatment maintained microbial diversity, promoted the growth and metabolism of potentially beneficial genera (e.g., Cyanobacteria, Bacillus, Paenibacillus, Hanseniaspora, Pichia), and suppressed pathogenic genera (e.g., Xylaria, Lasiodiplodia, Gibberella, Fusarium). These changes contributed to promote disease resistance and improve postharvest quality of litchi fruit. This study provides valuable insights into how microbial antagonists can regulate postharvest diseases and sets the groundwork for developing beneficial microbial consortia to enhance the postharvest safety and commercial value of litchi fruit.