Effects of Meyerozyma guilliermondii PJ15 on the biocontrol of Penicillium crustosum causing postharvest decay in Orah and its influence on the microbial diversity of Orah

Objectives: This study aims to isolate biocontrol microorganisms that inhibit Penicillium crustosum and explore their effects on microbial control and microbial diversity changes in P. crustosum causing postharvest decay in Orah. Materials and Methods: The biocontrol effect was verified by confrontation experiments. The microbial diversity was analyzed using high-throughput sequencing technology. Metabolomic analysis was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results: A strain of Meyerozyma guilliermondii PJ15 that strongly inhibited P. crustosum was isolated from the grape surface, which could effectively inhibit the mycelial growth and green spore production of P. crustosum. PJ15 could reduce the sourness and nutrient loss of Orah caused by P. crustosum. Compared with the control, PJ15 treatment increased the pH by 11.32%, the soluble protein content by 163.64%, the ascorbic acid content by 160.84%, and the total soluble sugar content by 203.53%. Microbial diversity analysis showed that PJ15 has a relatively small effect on the bacterial composition and diversity on the surface of Orah but has a significant impact on the fungal composition and diversity. It can increase the fungal diversity of Orah invaded by P. crustosum, increase the density of fungal interaction networks, and form a stronger coexisting survival interaction network. The vaccination of PJ15 downregulated the differential metabolite 5,6-epoxytetraene, which showed a positive correlation with P. crustosum and a negative correlation with PJ15. Conclusions: Meyerozyma guilliermondii PJ15 has a strong inhibitory effect on the growth of P. crustosum and has a significant impact on the fungal composition and diversity on the surface of Orah. It has potential for biocontrol of P. crustosum causing postharvest decay in Orah.