Pichia terricola N-4 as a biocontrol Agent: Mold inhibition and effects on the volatilome and fungal community of cigar tobacco leaves

• Pichia terricola N-4 suppresses mold on postharvest cigar tobacco leaves. • GC-IMS reveals N-4 alters volatile profiles. • N-4 reduces fungal diversity and enriches the biocontrol yeast. • Strong correlation between Pichia and key VOCs like 2-methyl-1-butanol. • N-4 presents a promising biocontrol strategy for postharvest tobacco protection. Postharvest mold contamination poses a significant threat to the quality and economic value of cigar tobacco leaves. This study evaluated the efficacy of the biocontrol yeast Pichia terricola N-4 (N-4) at different concentrations (10 6 , 10 7 , and 10 8 CFU/mL, designated JK1, JK2, and JK3) for inhibiting mold. The impact of N-4 on volatile organic compounds (VOCs) and the fungal community of cigar tobacco leaves was investigated using gas chromatography-ion mobility spectrometry (GC-IMS) and high-throughput sequencing (HTS). Results indicated that JK2 and JK3 treatments significantly inhibited mold growth. Importantly, olfactory sensory evaluation confirmed that the effective JK2 treatment successfully controlled mold without introducing off-odors. Furthermore, a double-dish assay demonstrated that N-4 completely inhibited mold outbreaks on cigar tobacco leaves via a gaseous fumigation effect, without requiring direct physical contact. GC-IMS identified 74 VOCs, with 17 exhibiting significant differences ( P < 0.05) among treatments. The relative contents of 2-methyl-1-butanol and 2-methyl-1-propanol were significantly elevated in N-4 treated samples and showed strong positive correlations with the genus Pichia . Fungal community analysis revealed a decrease in α-diversity in all treated samples (MB7, JK1, JK2, JK3) compared to MB0. Although Aspergillus remained the dominant genus natively, the relative abundance of Pichia increased significantly in the high-concentration N-4 treatment (JK3). Spearman correlation analysis revealed strong positive associations between Pichia and key VOCs. This study clarified the inhibitory effects of N-4 and provided systematic guidance for its safe, eco-friendly application in cigar tobacco mold prevention.