Effect of pesticide application on the community structure of wine yeasts during spontaneous fermentation

Abstract:

[Background] Yeast is a very important microorganism in wine fermentation. Its diversity and population composition play an important role in wine quality. There are many factors that affect the distribution and presence of yeast flora in wine. However, the influence of grape field management, for example the use of pesticides, on wine yeast community structure has not been reported yet. [Objective] We studied the effect of pesticide application on the community structure of wine yeasts during spontaneous fermentation. [Methods] Methods of pure culture, molecular biology identification and Illumina MiSeq metagenomic sequencing were used. [Results] In the spontaneous fermentation broth of grape samples without internal absorption chemical pesticides, 7 genuses (8 species) of yeast strains including Pichia, Hanseniaspora, Schizosaccharomyces, Candida, Saccharomyces, Zygoascus, and Issatchenkia were isolated and identified, while the result of metagenomic sequencing confirmed the dominance of Pichia (29.42%), Saccharomyces (21.91%), Issatchenkia (17.99%), Hanseniaspora (12.10%), Candida (7.47%), Zygosaccharomyces (5.32%), Schizosaccharomyces (3.07%), and Aureobasidium (0.29%). In the spontaneous fermentation broth of grape samples with conventional chemical pesticides, 5 genuses (6 species) of yeast strains including Pichia, Hanseniaspora, Schizosaccharomyces, Candida, and Cryptococcus were isolated and identified, while the result of Illumina MiSeq sequencing showed that Pichia (41.66%), Hanseniaspora (21.54%), Candida (19.11%), Zygosaccharomyces (7.78%), Schizosaccharomyces (4.04%), Cryptococcus (3.21%), Saccharomyces (1.12%), and Aureobasidium (0.49%) were involved in the fermentation. [Conclusion] Yeast community compositions in the two samples were significantly different, indicating that pesticide application on grapes had great influence on the community structure of wine yeasts during spontaneous fermentation.