Analysis of yeast diversity during spontaneous fermentation of red and white pitaya

Yeast communities during spontaneous fermentation of red and white pitaya were characterised and compared to provide a reference for the isolation of pitaya yeast strains. Using Illumina MiSeq high-throughput sequencing technology, we investigated the composition and diversities of yeast communities during five stages of spontaneous fermentation (1, 3, 5, 7, and 15 d), and the results showed 584,055 and 699,120 valid sequences from red and white pitaya, respectively. The sequences were classified into 86 and 42 operational taxonomic units, then assigned to 69 species in 49 genera (red pitaya) and 37 species in 32 genera (white pitaya). Taxonomic composition and diversity analysis results showed high yeast diversity during the early stage of spontaneous fermentation (RF1) for red pitaya, and during the middle stage (WF5) for white pitaya fermentation. The dominant yeast species was unclassified_o_Saccharomycetales in red pitaya, and Clavispora opuntiae in white pitaya, and these species showed opposite trends during red and white pitaya fermentation. One-way ANOVA showed highly significant differences in unclassified_o_Saccharomycetales (p ≤ 0.01) in red pitaya, and in Clavispora opuntiae (p ≤ 0.001) in white pitaya across the five spontaneous fermentation stages. In addition, phylogenetic analysis revealed that unclassified_o_Saccharomycetales and Clavispora opuntiae were positioned farthest from other yeast species. Overall, yeast community diversity during spontaneous fermentation was higher in red rather than white pitaya.