Grape berry microbiota cultivar Corvina withering process Metagenomic assembly

Metagenomic analysis of the grape berry microbiota growing on grape bunch (cultivar Corvina) during withering process. Samples of grapes of cv. Corvina were collected from a drying loft . Grapes were harvested in September 2013 and placed in October on wooden racks in the loft for the grape drying until January 2014. Grape drying was carried out in two ways: the traditional way, where temperature ranges, relative humidity, ventilation and grape weight loss were monitored by maintaining ideal conditions for the grape drying within the loft as defined by the average climate parameters; and the accelerated way, where, besides the parameters detailed above, a fan was placed closed to the grapes to promote a faster grape drying. Grape drying was monitored and samples were collected when both the batches of grapes (the traditional and accelerated) reached 30% of the weight loss (after 61 and 109 days, respectively). Small amounts of sound berries from each wooden rack of both the traditional and the accelerate batch were randomly collected, pooled together (150 g) in order to make the sample representative, placed in sterile plastic bags and then conserved at 4°C until the following laboratory analysis. Berries were washed in a sterile 250 mL flask containing a solution of Tryptic Soy Broth (10 g/L) and Tween 80 (2 mL/L) to release the microorganisms from the berry surface (3 h with slow shaking). The two washing solutions were then filtered with cellulose nitrate filters (0,45 µm) and then conserved at 4°C until the metagenomic DNA extraction.