Assessment of wine microbial diversity using ARISA and cultivation-based methods

This study investigated the microbial diversity present in grape juice and in the early stage of alcoholic fermentation. The grapes were obtained from a South African biodynamic vineyard in three consecutive vintages (2012, 2013, and 2014). Culture-dependent and culture-independent approaches were used to investigate yeast and bacterial diversity. For the culture-independent approach, Automated Ribosomal Intergenic Spacer Analysis (ARISA) was employed. Using basic microbiological analyses, 4, 12, and 15 yeast species were obtained in 2012, 2013, and 2014, respectively. In contrast, ARISA profiles revealed 13 fungal peaks for the year 2013 and 14 for 2012 and 2014. Out of 14 peaks in 2012, two peaks were identified as probable corresponding fungal Operational Taxonomical Units (OTUs) and six peaks were identified for the years 2013 and 2014. The bacterial ARISA revealed ten, seven, and 12 peaks for these three years, respectively. Furthermore, the same technique was used to assess the evolution of the fungal community in the first three days of fermentation of the 2013 grape must. The data show that the yeast population diversity declined rapidly and revealed 12, 10, and 6 peaks for days 1, 2, and 3, respectively. The study demonstrated the suitability of ARISA for studying microbial diversity and dynamics in grape must and during wine fermentation.