Adaptation of Lactobacilli towards low ph and SO₂ to develop MLF in base musts for sparkling wines

The vineyard is capable of fixing carbon in its permanent structure from atmospheric carbon dioxide, through the process of gas exchange and the performance of photosynthesis. The photosynthetic capacity of the vineyard depends on the water resources that the plant may have at its disposal, so the amount of dry matter, derived from the processed photosynthates, that it can store will depend on the water regime of the crop, both in the annually renewable organs as in permanent parts.

Climate change results in increasing water stress due to co-effects of rising evapotranspiration (ET) and decreased precipitation over the past 65 years (Spinoni et al. 2019).

Climate change constitutes an enormous challenge for humankind and for all human activities, viticulture not being an exception. Long-term strategic changes are probably needed the most, but growers also need to deal with short-term changes: summers that are getting progressively warmer, earlier harvest dates and higher pH in musts and wines. In the last 10-15 years, a relevant corpus of research is being developed worldwide in order to evaluate to which extent extreme canopy management operations, aimed at reducing leaf area and, thus, limiting the source to sink ratio, could be useful to delay ripening. Although extreme canopy management can result in relevant delays in harvest dates, longer term studies, as well as detailed analysis of their implications on carbohydrate reserves, bud fertility and future yield are desirable before these practices can be recommended.

Oenococcus oeni is the main Lactic Acid Bacteria responsible for malolactic fermentation, converting malic acid into lactic acid and carbon dioxide in wines. Following the alcoholic fermentation, this second fermentation ensures a deacidification and remains essential for the release of aromatic notes and the improvement of microbial stability in many wines. Nevertheless, wine is a harsh environment for microbial growth, especially because of its low pH (between 2.9 and 3.6 depending on the type of wine) and nutrient deficiency. In order to maintain homeostasis and ensure viability, O. oeni possesses different cellular mechanisms including organic acid metabolisms which represent also the major pathway to synthetize energy in wine.

The research was carried out in the ‘Chianti Classico’ area and it was part of the ‘Chianti Classico 2000’ research project. The performances ‘Sangiovese’ grapevine