Analysis of Microbial Community Diversity on the Epidermis of Wine Grapes in Manasi's Vineyard, Xinjiang

Abstract

Epiphytic microbial communities significantly impact the health and quality of grape berries. This study utilized high-performance liquid chromatography and high-throughput sequencing to explore the epiphytic microbial diversity and physicochemical indicators in nine different wine grape varieties. In total, 1,056,651 high-quality bacterial 16S rDNA sequences and 1,101,314 fungal ITS reads were used for taxonomic categorization. Among the bacteria, Proteobacteria and Firmicutes were the dominant phyla, and Massilia, Pantoea, Pseudomonas, Halomonas, Corynebacterium, Bacillus, Anaerococcus, and Acinetobacter were the dominant genera. Among the fungi, Ascomycota and Basidiomycota were the dominant phyla, and Alternaria, Filobasidium, Erysiphe, Naganishia, and Aureobasidium were the dominant genera. Notably, Matheran (MSL) and Riesling (RS) exhibited the highest microbial diversity among the nine grape varieties. Moreover, pronounced differences in epiphytic microorganisms in red and white grapes suggested that the grape variety significantly influences the structure of surface microbial communities. Understanding the composition of epiphytic microorganisms on the grape skin can provide a direct guide to winemaking.

Keywords: Illumina high-throughput sequencing; grape surface microorganisms; microbial diversity; wine grapes.

Figure 1

Overall differences in pH, soluble solids content (a), total sugars, and total acidity (b) of different wine grapes.

Figure 2

Differences in the organic acids (a) and soluble sugars (b) in different wine grape samples.

Figure 3

Venn diagrams of the fungal (a) and bacterial (b) OTUs among different wine grape samples.

Figure 4

Differences in fungal (a) and bacterial (c) communities at the phylum level. The relative abundances of the top 15 fungi (b) and bacteria (d) at the genus level.

Figure 5

Heatmap of the top 35 abundant fungal genera in different grape samples. Samples are clustered according to the similarity between their constituents and arranged in horizontal order. Red and blue represent the more and less abundant genera in the corresponding group, respectively.

Figure 6

Heatmap of the top 35 abundant bacterial genera in different grape samples. Samples are clustered according to the similarity among their constituents and arranged in horizontal order. Red and blue represent the more and less abundant genera in the corresponding group, respectively.

Figure 7

Principal component analysis (PCA) scatter plot of the fungal (a) and bacterial communities (b) in the samples.

Figure 8

Co-occurrence and co-exclusion relationships between different bacteria (a) and fungi (b) and between bacteria and fungi (c). The Pearson rank correlation matrix showing the abundances of the top 30 fungi and bacterial genera is depicted. Strong and weak correlations are indicated by the large and small circles, respectively. The color of the scale bar denotes the nature of the correlation; 1 indicates a perfect positive correlation (red) and −1 indicates a perfect negative correlation (green). Significant correlations (|r| > 0.7, p < 0.01) and (|r| > 0.9, p < 0.01) are indicated by * and **, respectively.