Analysis of fungal dynamic changes in the natural fermentation broth of ‘Kyoho’ grapes based on high-throughput sequencing

The ‘Kyoho’ grape (Vitaceae, Plantae) has large ears, plenty of flesh, and rich nutrition, and is planted across a large area in China. There are few reports on this variety in winemaking, especially on the dynamic changes of fungi in the wine fermentation broth. In this study, we used the ‘Kyoho’ grapes as raw materials and adopted a high throughput to analyze dynamic changes in fungal species composition of the natural fermentation broth at four time points: day one (D1P), day three (D3P), day five (D5P), and day fifteen (D15P). Changes in fungal metabolic pathways and the dynamic changes of dominant yeast were also analyzed. A total of 78 families, 110 genera, and 137 species were detected, in the natural fermentation broth samples. The control check (CK) had 49 families, 60 genera, and 72 species. A total of 66 differential metabolic pathways were enriched; of those 66, 41 pathways were up-regulated compared to CK, such as pyrimidine deoxyribonucleotides biosynthesis from CTP (PWY 7210), CDP-diacylglycerol biosynthesis I (PWY 5667), and chitin degradation to ethanol (PWY 7118). Changes in fungal metabolic pathways were in line with the dynamic changes of dominant yeast species in the whole process of fermentation. Pichia kluyveri , P. membranifaciens , and Citeromyces matritensis are the dominant species in the later stages of natural fermentation. These yeast species may play vital roles in the ‘Kyoho’ wine industry in the future.