Variable characteristics of microbial communities and volatile organic compounds during post-harvest storage of wild morel mushrooms

Abstract

Wild morel mushroom is one of the most popular mushrooms, but fresh morels have a short shelf life and are highly susceptible to microbial influences that can lead to spoilage and changes in volatile organic compounds. Therefore, the microbial communities (bacteria and fungi) were studied by high-throughput sequencing technology on wild morel mushrooms in a post-harvest environment at 4 ℃. The volatile organic compounds (VOCs) of wild morel mushrooms were evaluated by headspace solid-phase microextraction (HS-SPME) in combination with gas chromatography-mass spectrometry (GC-MS) during storage. The results showed that there were 41 given genera of bacteria and 48 given genera of fungi with abundance > 0.01% during the whole storage period. Among them, bacteria: Pseudomonas, Pedobacter and Flavobacterium; fungi: Cystofilobasidium, Aspergillus and Mucor had a greater impact on wild morel mushrooms during storage, especially Pseudomonas, whose abundance was consistently elevated and accounted for the largest share (47.51–73.73%). The main VOCs of wild morel mushrooms consist of aldehydes, alcohols, alkanes, ketones, phenols, esters and acids. Among them, 3-Octanone is predominant, but its content has been decreasing. The analysis showed a strong correlation between microorganisms and VOCs (P < 0.05, |r| > 0.9). Among them, Pseudomonas was correlated with 4 VOCs; Cystofilobasidium with 8 VOCs; Aspergillus with 7 VOCs; and Mucor with 7 VOCs. This suggests that microbes are crucial to the degradation and VOCs of morels during spoilage. The findings of the research provide information database for post-harvest preservation of morel mushrooms and efficient control of their spoilage.